fix(audit): non-Documenso backlog sweep — port-binding, NULLS NOT DISTINCT, custom merge tokens, company docs

Wave through the remaining audit-final-deferred items that aren't blocked
on the back-burnered Documenso work.

Multi-tenant isolation:
- Storage proxy ProxyTokenPayload gains optional `p` (port slug) claim;
  verifier asserts `key.startsWith(${p}/)`. Defense-in-depth against a
  buggy issuer in some future code path that mixes port scopes — every
  storage key generated by generateStorageKey() already prefixes the
  slug. document-sends opts in for 24h emailed download links; other
  callers continue working unchanged via the optional field.

DB schema reconciliation:
- Migration 0047 rebuilds system_settings unique index with NULLS NOT
  DISTINCT (Postgres 15+) so global settings (port_id IS NULL) are
  uniquely keyed by `key` alone. Surfaced + dedupe'd 65 duplicate
  (storage_backend, NULL) rows that had accumulated from race-prone
  delete-then-insert patterns in ocr-config / settings / residential-
  stages / ai-budget services. All four services converted to true
  onConflictDoUpdate upserts so the race window is closed.

API uniformity:
- Response shape standardization: 16 routes converted from
  `{ success: true }` to 204 No Content. CLAUDE.md documents the
  convention (`{ data: <T> }` for content, 204 for empty mutations,
  portal-auth retains `{ success: true }` for the frontend's auth chain).
- req.json() → parseBody() migration across 9 admin/CRM routes
  (custom-fields, expenses/export ×3, currency convert,
  search/recently-viewed, admin/duplicates, berths/pdf-{upload-url,
  versions, parse-results}). Uniform 400 error shapes for
  ZodError-flagged bodies.

Custom-fields merge tokens (shipped end-to-end):
- merge-fields.ts gains CUSTOM_MERGE_TOKEN_RE + helpers for the
  `{{custom.<fieldName>}}` shape.
- document-templates validator accepts the dynamic shape alongside
  the static catalog tokens.
- document-sends.service mergeCustomFieldValues resolver fetches
  per-port custom_field_definitions for client/interest/berth contexts
  and substitutes stored values keyed by `{{custom.fieldName}}`.
- custom-fields-manager amber banner updated to reflect that merge
  tokens now expand (search index + entity-diff remain documented
  design limitations).

/api/v1/files cross-entity filtering:
- Validator + listFiles + uploadFile accept companyId AND yachtId
  alongside clientId. file-upload-zone propagates both.
- New CompanyFilesTab component mirrors ClientFilesTab; restored as a
  visible Documents tab in company-tabs.tsx (was a hidden stub).

Inline TODOs:
- Reviewed remaining two TODOs (per-user reminder schedule, import
  worker handlers). Both are placeholders for future feature surfaces,
  not bugs — per-port digest works for every customer; nothing
  currently enqueues import jobs (verified). Annotated in BACKLOG.

BACKLOG.md updated to reflect what landed and what's still pending
(Documenso-related items still bundled with the back-burnered phases).

Tests: 1185/1185 vitest, tsc clean.

CLAUDE.md

@@ -106,6 +106,8 @@ src/
 - **Send-from accounts (sales send-outs):** Configurable via `system_settings`; defaults to `sales@portnimara.com` for human-touch and `noreply@portnimara.com` for automation. SMTP/IMAP passwords are AES-256-GCM encrypted at rest; the API never returns decrypted secrets — only `*PassIsSet` boolean markers. Send-out audit goes to `document_sends` (separate from `audit_logs` because of volume + binary refs). Body markdown is XSS-safe via `renderEmailBody()` (escape-then-allowlist; tested against the standard XSS vector list). Rate limit: 50 sends/user/hour individual. Pre-send size threshold: files > `email_attach_threshold_mb` ship as a 24h signed-URL link rather than an attachment (avoids the duplicate-send race from async bounces). The download-link fallback HTML-escapes the filename to prevent injection from admin-supplied brochure names. Bounce monitoring requires IMAP credentials in addition to SMTP — without them, the size-rejection banner stays disabled.
 - **NocoDB berth import:** `pnpm tsx scripts/import-berths-from-nocodb.ts --apply --port-slug port-nimara` re-imports from the legacy NocoDB Berths table. Idempotent: rows where `updated_at > last_imported_at` (the "human edited this since last import" guard) are skipped unless `--force`. Adds `--update-snapshot` to also rewrite `src/lib/db/seed-data/berths.json`. Uses `pg_advisory_xact_lock` so two simultaneous runs serialize. Pure helpers in `src/lib/services/berth-import.ts` are unit-tested.
 - **Routes:** Multi-tenant via `[portSlug]` dynamic segment. Typed routes enabled.
+- **API response shapes:** Conventional envelope is `{ data: <T> }` for any endpoint that returns content (read OR write). Mutations that return nothing emit `204 No Content` (`new NextResponse(null, { status: 204 })`). Don't use `{ success: true }` for CRM mutations — it was a legacy pattern, normalized away in 2026-05-07. Public portal-auth endpoints are an exception: they return `{ success: true }` because the frontend needs a non-error JSON body to chain on. List/paginated reads return `{ data: <T[]>, total?, hasMore? }` (see `/api/v1/clients` for the shape). Errors always go through `errorResponse(error)` from `@/lib/errors` so request-id propagation and the audit-tier mapping stay uniform.
+- **Body parsing:** Always use `parseBody(req, schema)` from `@/lib/api/route-helpers` instead of `await req.json(); schema.parse(body)`. The helper returns a uniform 400 with field-level errors that the frontend's `toastError` hook recognizes; raw `req.json` + `schema.parse` produces a generic 500 because the ZodError isn't caught in the same shape.
 - **Pre-commit:** Husky + lint-staged runs ESLint fix + Prettier on staged `.ts`/`.tsx` files. The hook also blocks `.env*` files (including `.env.example`) from being committed; pass them via a separate workflow if needed.
 
 ## Schema migrations during dev