feat(uat-batch): M43 — form-template bindings + inline field history

Closes plan item 43 (Form-template fields bind to Interest/Client data —
autofill, override-preservation history, dual-surface audit trail).

Phase 1 — Editor:
- New bindable-fields catalog (src/lib/templates/bindable-fields.ts):
  client/yacht/interest paths, each tagged with the entity, column, and
  default input type. Source of truth for what can bind + what
  interest_field_history.field_path strings the writers should use.
- formFieldSchema gains optional bindTo, validated against the catalog
  as an allow-list (no arbitrary paths sneak through).
- form-template-form admin sheet: per-field "Bind to" dropdown grouped
  by entity, auto-derives label/key/type when a binding is picked,
  shows "Autofills from + writes back to {label} . {path}" badge.

Phase 2 — Runtime + history writes:
- supplemental-forms.service.applySubmission already wrote
  interest_field_history rows for client name/email/address from the
  earlier 0081 migration session. Extended to also capture phone +
  yacht (name, length, width, draft) diffs that were silently going
  to the entity without an audit row, and to push insert-path
  overrides for the no-existing-address case.
- Field paths aligned with the bindable-fields catalog so detail-page
  lookups work via exact-match WHERE field_path = ?.

Phase 3 — Inline history surface:
- New /api/v1/clients/[id]/field-history (mirror of the existing
  interests endpoint).
- shared/field-history: FieldHistoryProvider wraps a detail tab and
  fires a single keyed GET; FieldHistoryIcon consumes the context and
  renders a small clock affordance only when at least one override
  exists, opening a popover with the reverse-chrono diff list.
- Client + Interest detail Overview tabs wrapped in the provider;
  EditableRow gains an optional historyPath prop; ContactsEditor
  renders the icon next to the canonical primary email/phone.

1454/1454 vitest, tsc clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/validators/form-templates.ts

@@ -1,5 +1,7 @@
 import { z } from 'zod';
 
+import { BINDABLE_PATHS } from '@/lib/templates/bindable-fields';
+
 export const formFieldSchema = z.object({
   key: z.string().min(1).max(80),
   label: z.string().min(1).max(200),
@@ -7,6 +9,19 @@ export const formFieldSchema = z.object({
   required: z.boolean().optional().default(false),
   options: z.array(z.string()).optional(),
   helpText: z.string().optional(),
+  /**
+   * Optional binding to an Interest/Client/Yacht column. When set, the
+   * supplemental-form runtime prefills the field from the linked entity
+   * AND writes the submitted value back to that column on apply (with an
+   * `interest_field_history` row capturing the override). Validated
+   * against `BINDABLE_FIELDS` so unknown paths can't sneak in.
+   */
+  bindTo: z
+    .string()
+    .refine((v) => BINDABLE_PATHS.includes(v), {
+      message: 'Unknown bindable path',
+    })
+    .optional(),
 });
 
 export const createFormTemplateSchema = z.object({