feat(17-02): repeater field and dependent dropdown states

- RepeaterField: rows with drag handle, index, titleFrom title, error chip,
  move up/down (buttons, ArrowUp/ArrowDown on the handle, native drag and
  drop), expand/collapse, remove (asks only for a row holding a value),
  add with nested defaults, maxItems counter, empty state, collapse all;
  every change edits form state only
- 422 row paths (content.3.answer) open the row, mark it and focus the
  nested control; the banner no longer repeats row messages
- DropdownField dependsOn: waiting, loading, not used, empty, loaded with
  depth indent, failed with retry; cached per sibling value, last request
  wins, a stale value is cleared after a sibling change and announced
- FormView provides form feedback (errors and notices by row path, the
  polite live region, its confirm dialog) and the options cache; FormGrid
  provides the sibling scope for repeater rows
- repeater.* and form.dependent_* phrase keys (en, pl), smoke specs, docs

admin/src/components/form/formContext.ts

@@ -5,7 +5,7 @@
 // provider (settings pages) gets the defaults of the injecting control.
 import { ref, type InjectionKey, type Ref } from 'vue'
 import type { FileRoutes } from '../../api/files'
-import type { AdminRecord } from '../../api/types'
+import type { AdminDependentOptionsResult, AdminRecord, FormField } from '../../api/types'
 
 /** Read-only view of the form's current values. */
 export const FORM_VALUES: InjectionKey<Readonly<Ref<AdminRecord>>> = Symbol('summer.form.values')
@@ -113,3 +113,39 @@ export const FIELD_UPLOAD_RESULT_EVENT = 'summer-upload-result'
 
 /** How long a widget waits for its custom element to be defined. */
 export const WIDGET_TIMEOUT = 5000
+
+/**
+ * The record form's feedback (Phase 17, D-07, D-08): errors and save notices
+ * keyed by field name or row path (`<repeater>.<index>.<nested>`), the form's
+ * single polite live region, and its confirm dialog. FormView provides it; a
+ * control without it (settings pages) announces nothing and never asks.
+ */
+export interface FormFeedback {
+  errors: Readonly<Ref<Record<string, string[]>>>
+  notices: Readonly<Ref<Record<string, string[]>>>
+  /** Drops the error lines of one key: the administrator edited that value. */
+  clearError(key: string): void
+  /** Announces text in the form's polite live region. */
+  announce(text: string): void
+  /** Asks through the form's ConfirmDialog; resolves true on confirm. */
+  confirm(request: { message: string; confirmLabel?: string; danger?: boolean }): Promise<boolean>
+}
+
+export const FORM_FEEDBACK: InjectionKey<FormFeedback> = Symbol('summer.form.feedback')
+
+/**
+ * The fields a FormGrid renders and their values (D-08): a dependent
+ * dropdown reads its sibling here. A repeater row's grid provides the row's
+ * fields and values, and `path` names a field for its routes
+ * (`<repeater>.<field>` in a row).
+ */
+export interface FieldScope {
+  fields: Readonly<Ref<readonly FormField[]>>
+  values: Readonly<Ref<AdminRecord>>
+  path(name: string): string
+}
+
+export const FIELD_SCOPE: InjectionKey<FieldScope> = Symbol('summer.form.fieldScope')
+
+/** Dependent options per field path and sibling value, for the life of a form view. */
+export const DEPENDENT_CACHE: InjectionKey<Map<string, AdminDependentOptionsResult>> = Symbol('summer.form.dependentCache')