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

admin/tests/fixtures/roster.record.json

@@ -1,5 +1,5 @@
 {
-  "data": { "id": 1, "name": "Ada Lovelace", "email": "ada@example.test", "joined_ip": "203.0.113.7" },
+  "data": { "id": 1, "name": "Ada Lovelace", "email": "ada@example.test", "slug": "ada-lovelace", "joined_ip": "203.0.113.7" },
   "meta": {
     "labels": {},
     "actions": [