feat(19.6.1-01): Administrators screen and cross-controller record actions

- pact.HasAdminActionExtensions / AdminActionExtension: plugins add record
  actions to any admin controller by ID, merged at boot before permission
  validation (unknown target, no preview, duplicate name stop the boot)
- internal summercms.cabana pseudo-plugin, appended only when some plugin
  registers admin controllers: Administrators list and preview, settings
  link under System, backend.manage_users and backend.manage_roles with no
  role grants
- backend::lang user, user.role and permissions copy (en, pl)
- smoke tests: compile-time seam and settings, Postgres list/preview/action

modules/pact/README.md

@@ -27,7 +27,7 @@ Use cases:
 - Backend registration data: `pact.Permission`, `pact.NavigationItem` and `pact.SettingsItem`, exposed through `pact.HasPermissions`, `pact.HasNavigation` and `pact.HasSettings`. A settings entry is either a singleton form or a link that opens an admin controller from the Settings page. A `pact.NavigationItem.Visible` func hides a navigation entry at request time (nil = always listed).
 - Personal API token scopes: `pact.TokenScope` and `pact.HasTokenScopes`, so a plugin declares named scopes (permissions and HTTP methods) that administrators can assign when creating a personal API token.
 - Admin controller contracts: `pact.AdminController`, `pact.HasAdminControllers`, `pact.AdminAssets` (embedded Winter-shaped admin YAML), `pact.AdminPermissioned` and `pact.AdminRecordSource`.
-- Admin extension contracts, so a plugin extends the compiled admin SPA without a Node build: `pact.AdminClientAssets` (per-controller JS and CSS from the plugin's embedded `assets/` tree, Winter's `addJs`/`addCss`), `pact.HasAdminActions` with `pact.AdminAction`, `pact.AdminActionInput` and `pact.AdminActionResult` (named toolbar and widget actions whose routes, CSRF check, permissions and record scoping the framework owns), `pact.HasAdminBulkActions` with `pact.AdminBulkAction`, `pact.AdminBulkActionInput` and `pact.AdminBulkActionResult` (named actions on the rows selected in a list, which receive records the framework loaded through the list scope, never ids; a `Detached` action runs outside the framework transaction), `pact.HasAdminRecordActions` with `pact.AdminRecordAction`, `pact.AdminRecordActionInput` and `pact.AdminRecordActionResult` (named actions on one record, each with an `Applies` rule for the record's state), and `pact.AdminPartialData` (the curated view model a partial template renders).
+- Admin extension contracts, so a plugin extends the compiled admin SPA without a Node build: `pact.AdminClientAssets` (per-controller JS and CSS from the plugin's embedded `assets/` tree, Winter's `addJs`/`addCss`), `pact.HasAdminActions` with `pact.AdminAction`, `pact.AdminActionInput` and `pact.AdminActionResult` (named toolbar and widget actions whose routes, CSRF check, permissions and record scoping the framework owns), `pact.HasAdminBulkActions` with `pact.AdminBulkAction`, `pact.AdminBulkActionInput` and `pact.AdminBulkActionResult` (named actions on the rows selected in a list, which receive records the framework loaded through the list scope, never ids; a `Detached` action runs outside the framework transaction), `pact.HasAdminRecordActions` with `pact.AdminRecordAction`, `pact.AdminRecordActionInput` and `pact.AdminRecordActionResult` (named actions on one record, each with an `Applies` rule for the record's state), `pact.HasAdminActionExtensions` with `pact.AdminActionExtension` (a plugin adds record actions to any admin controller by controller ID, one it does not own included; they are offered on that controller's preview screen after the owner's), and `pact.AdminPartialData` (the curated view model a partial template renders).
 - Plugin field types: `pact.HasFormFieldTypes` returns `pact.FormFieldType` entries, admin form field types any controller's `fields.yaml` uses by a short alias (`type: notes`). A type names its custom element, its scripts and styles, its own option keys and its Go funcs: `Decode` turns a submitted `pact.FormFieldValue` into a `pact.FormFieldDecoded` (the value to store plus optional `pact.FormFieldNotice` messages for the administrator, such as what a sanitizer removed) or refuses it with a `pact.FormFieldError`; `Load` serves the stored value to the element, `ListValue` formats a list column, and `Upload` stores a file from a `pact.FormFieldUpload` and answers a `pact.FormFieldUploadResult`. The admin framework owns the routes, permissions, record scope, locale storage of a translatable type and the localization of notices.
 - Optional admin hooks a controller or model can implement: list and form query scoping (`pact.ListExtendQuery`, `pact.FormExtendQuery`), list row states (`pact.ListRowStates` with the fixed `pact.RowState` set `pact.RowStateDeleted`, `pact.RowStateNegative` and `pact.RowStateDisabled`), values of unstored list columns filled once per page (`pact.ListExtendRecords`), the record title of the form and preview screens (`pact.FormRecordTitle`), create, update and delete hooks (`pact.FormBeforeCreate`, `pact.FormAfterUpdate`, `pact.FormBeforeDelete` and their siblings), a hook after a reorder save (`pact.ReorderAfterSave`), form-only fields that reach those hooks without being model columns (`pact.FormVirtualFields`), validation rules per operation for admin saves (`pact.FormRules`), relation hooks (`pact.RelationExtendManageQuery`, `pact.RelationExtendOptionsQuery`, `pact.RelationBeforeLink`), relation child hooks around creating, updating and deleting a related record (`pact.RelationBeforeCreate`, `pact.RelationAfterCreate`, `pact.RelationBeforeUpdate`, `pact.RelationAfterUpdate`, `pact.RelationBeforeDelete`, `pact.RelationAfterDelete`), filter scopes (`pact.FilterScope`, `pact.FilterOptions`) and dropdown options (`pact.DropdownOptionsProvider`).
 - Dependent dropdown options: `pact.DependentOptionsProvider` answers a `pact.DependentOptionSet` (whether the sibling's value takes a choice at all, and the choices) for a dropdown with `dependsOn`, from the submitted values of its siblings and with a context, so the choices can come from the database; the admin framework calls it for the options route and again on every save. `pact.Option.Depth` indents a choice taken from a tree.
@@ -137,6 +137,8 @@ func (p *Plugin) Schedule() []pact.ScheduledCommand {
 | `pact.AdminRecordActionInput` | What a record action receives: `RecordID` and `Record`, the record loaded and row-locked through the form scope. |
 | `pact.AdminRecordActionResult` | What a record action returns: an optional message for the toast. |
 | `pact.HasAdminRecordActions` | Registers a controller's record actions for the `recordActions` list of `config_form.yaml`. |
+| `pact.AdminActionExtension` | Record actions a plugin adds to one admin controller by its `Controller` ID; offered on the target's preview screen after the owner's actions, each checked against the target's `RequiredPermissions` and its own `Permissions`. |
+| `pact.HasAdminActionExtensions` | Implemented by a plugin (not a controller) that adds actions to admin controllers, its own or another plugin's. An unknown controller ID, a target without a preview block or a duplicate name stops the boot. |
 | `pact.ReorderAfterSave` | Optional controller hook `ReorderAfterSave(ctx, partition)`: runs after a reorder save wrote the new order, inside the same transaction (`cabana.TxFromContext` works); an error rolls the reorder back. |
 | `pact.AdminPartialData` | Supplies the view model a controller partial template renders; never the GORM model. |
 | `pact.HasFormFieldTypes` | Implemented by a plugin (not a controller) that registers admin form field types. |

modules/pact/capabilities.go

@@ -375,6 +375,38 @@ type HasAdminRecordActions interface {
 	AdminRecordActions() []AdminRecordAction
 }
 
+// AdminActionExtension adds actions to an admin controller that another
+// plugin owns, or that the plugin itself owns. Controller is the controller
+// ID (vendor.plugin.controller) of any activated plugin's admin controller,
+// the admin framework's own controllers included.
+//
+// RecordActions are offered on the target controller's preview screen after
+// the owner's record actions, in plugin activation order. Each one keeps its
+// own Permissions, Applies, Confirm and Danger and runs exactly like the
+// owner's record actions: the framework loads and row-locks the record
+// through the target's FormExtendQuery scope inside the action's transaction
+// and hands it to Run, which reads that transaction with
+// cabana.TxFromContext. An administrator needs the target controller's
+// RequiredPermissions and the action's own Permissions. A record action
+// carries no input beyond the record.
+//
+// The admin compiles extensions at boot, only when it is active (some
+// plugin registers admin controllers). An unknown controller ID, a target
+// without a preview block, a name the owner or an earlier extension already
+// registers on that controller, a reserved name (create, delete), a name that
+// is not an identifier, a missing Run or an empty Label stops the boot. Only
+// record actions are carried for now; the struct leaves room for more kinds.
+type AdminActionExtension struct {
+	Controller    string
+	RecordActions []AdminRecordAction
+}
+
+// HasAdminActionExtensions is implemented by plugins (not admin controllers)
+// that add actions to admin controllers by controller ID.
+type HasAdminActionExtensions interface {
+	AdminActionExtensions() []AdminActionExtension
+}
+
 // AdminPartialData supplies the view model a controller partial template
 // renders (config_list.yaml headerPartial, fields.yaml `type: partial`). name
 // is the partial name; record is the scoped record for a form partial on an