feat(12.1-02): password and form-only fields, rules per operation and preset

- pact.FormVirtualFields lists form fields that are not model columns: never
  bound, filled or projected; their values reach the Form hooks through
  cabana.VirtualFieldsFromContext when the field's context allows the operation
- type: password is a masked field that must be listed as virtual
- pact.FormRules supplies the rule set per operation and replaces the model's
  Rules() for admin saves; a rule on a virtual field sees the submitted value
- preset on a text field follows another text field on the create form
- SPA: PasswordField, preset handling in FormView, empty password left out of
  an update
- README, docs, OpenAPI document, TS types and dist updated

modules/cabana/testdata/roster/models/person/fields.yaml

@@ -7,6 +7,25 @@ fields:
         label: acme.roster::lang.people.email
         type: text
         span: right
+    slug:
+        label: acme.roster::lang.people.slug
+        type: text
+        preset: name
+    password:
+        label: acme.roster::lang.people.password
+        type: password
+        span: left
+        context: [create, update]
+    password_confirmation:
+        label: acme.roster::lang.people.password_confirmation
+        type: password
+        span: right
+        context: [create, update]
+    notify:
+        label: acme.roster::lang.people.notify
+        type: checkbox
+        default: true
+        context: create
     joined_ip:
         label: acme.roster::lang.people.joined_ip
         type: text