feat(documenso-phase-4): recipient configurator + field placement UI

Phase 4 lands the visual half of the Documenso build — the upload-
for-signing dialog the Contract + Reservation tabs hand off to. Four
files of new code; the existing tab placeholders point at it.

Files added:
- lib/services/document-field-detector.ts — Phase 4c auto-detect
  scanner. Uses pdfjs-dist to extract per-page text + positions, then
  matches anchor patterns (Signature, Date, Initials, Email, Name,
  underscore-runs) and produces percent-coordinate DetectedField
  rows. Recipient label inference walks ±100pt of each match for
  Buyer/Seller/Client/Witness/Notary keywords. Returns [] when the
  PDF is image-only; UI falls back to manual placement without an
  error. 6 unit tests pin the matching + coordinate math.

- app/api/v1/documents/auto-detect-fields/route.ts — multipart POST
  endpoint that delegates to detectFields(). Permission-gated by
  documents.send_for_signing.

- app/api/v1/documents/signing-defaults/route.ts — GET endpoint that
  surfaces just the per-port developer + approver display name/email
  + sendMode flag. No secrets exposed; lets the dialog prefill the
  recipient configurator without an admin-scoped settings read.

- components/documents/upload-for-signing-dialog.tsx — the Phase 4
  UI. Three-step state machine inside a single Dialog:
    1. select-file:  drop/click PDF picker + title input
    2. configure-recipients: client + developer + approver prefilled,
       rep can add/remove/reorder + change role (SIGNER/APPROVER/CC)
    3. place-fields: react-pdf renders the source PDF; auto-detect
       runs in the background on file load and seeds the overlay;
       rep places, drags, resizes, deletes, reassigns fields via the
       palette + side panel. Native DOM drag (no dnd-kit dependency
       added — the coordinate math stays obvious).
  Send fires POST /api/v1/interests/[id]/upload-for-signing (Phase 3
  service); success toast reflects port sendMode (auto fires the
  invite immediately, manual leaves it for the rep).

Files modified:
- components/interests/interest-contract-tab.tsx + reservation-tab.tsx:
  swap the ComingSoonDialog placeholder for the real
  UploadForSigningDialog with the matching documentType prop. The
  placeholder ComingSoonDialog helper is deleted from both.

- scripts/tsc-staged.mjs: pull src/types/**/*.d.ts into the temp
  staged-only tsconfig so side-effect CSS imports (e.g.
  react-pdf/dist/Page/AnnotationLayer.css) resolve via the existing
  declare-module shim. Without this fix the staged compile reports
  TS2882 even though the full tsc --noEmit pass passes.

Design choices noted in code comments:
- Native drag over dnd-kit: the field overlay's percent-based
  coordinate math is short enough that adding a drag library adds
  complexity without saving lines.
- Auto-detect on file-load (not on demand): runs immediately so the
  rep doesn't have to click a second button — empty result drops
  back to manual placement silently.
- Per-recipient color swatches indexed by signingOrder.
- Recipient seed via useMemo + user-event handler instead of
  useEffect → setRecipients (Wave 3 set-state-in-effect avoidance).

Server-side, Phase 3 plumbing handles the rest: tenant guard, magic-
byte verify, Documenso round-trip with per-port v1/v2 routing,
recipient signingToken capture for Phase 2 webhook cascade, auto-
send when port.sendMode === 'auto'.

Tests: 1334 → 1340 ✅ (6 new for the detector); tsc clean.

Deferred polish (Phase 6):
- Per-field metadata side panel for DROPDOWN/RADIO option lists
- Pinch-zoom + zoom-out controls on the field-placement canvas
- Recipient drag-reorder via dnd-kit
- Required toggle per field

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

scripts/tsc-staged.mjs

@@ -36,6 +36,13 @@ const tmpConfig = join(tmpDir, 'tsconfig.json');
 
 const relFiles = files.map((f) => relative(tmpDir, resolve(cwd, f)));
 
+// Pull in the project's ambient .d.ts files (css module shim,
+// react-pdf JSX augment, etc.) so side-effect imports like
+// `import 'react-pdf/dist/Page/AnnotationLayer.css'` resolve under the
+// staged-only compile. Without this, `include: []` would shut out
+// everything in src/types/ and tsc reports TS2882 for any CSS import.
+const ambientTypesGlob = relative(tmpDir, join(cwd, 'src/types')) + '/**/*.d.ts';
+
 writeFileSync(
   tmpConfig,
   JSON.stringify(
@@ -50,7 +57,7 @@ writeFileSync(
         types: ['node', 'react', 'react-dom'],
       },
       files: relFiles,
-      include: [],
+      include: [ambientTypesGlob],
     },
     null,
     2,