esign: ink-reproduction consent gate + patent-risk research

Consent gate (the legal linchpin from the wet-signature memo):
- migration 092 adds ink_consent/ink_consent_at/ink_consent_text to esign_records
- extract pure, unit-tested gate logic into esign-ink-consent.ts (DRY single
  source for route + signing page): isInkReproduction / inkConsentRequired /
  inkConsentSatisfied + verbatim client-safe INK_CONSENT_TEXT
- portal-esign-generic.ts: GET surfaces ink_reproduction + consent text; POST
  gates DRAWN signatures on ink-path docs on explicit consent, stores it
- signing page locks the signature block until consent is checked (drawn only)
- npi_provider marks cms855/cms10114 esign metadata ink_reproduction=true
- 33 unit checks: gate truth table + consent text omits all internal mechanics
  (plotter/machine/CMS/MAC/etc) and keeps required legal reassurances

Patent-risk memo (docs/legal/patent-risk-mechanical-wet-signature.md):
- prior-art-dated risk analysis (autopen 1803/1942, plotters, CNC = public domain
  => low risk on core concept; e-sign workflow space litigious)
- firsthand recent-grant sweep (1.58M USPTO grants 2021-2025, queried via DuckDB):
  ZERO patents on machine-applies-signature-in-ink; e-sign players hold only
  electronic-workflow patents. Not an FTO; flags where attorney search is needed

api/migrations/092_esign_ink_consent.sql

@@ -0,0 +1,28 @@
+-- 092: Ink-reproduction consent on signature records.
+--
+-- The Standard (no-login) CMS filing path reproduces the signer's OWN captured
+-- signature strokes in real ink on the printed form (pen plotter) so the mailed
+-- application carries an original ink signature. Per the legal-risk research
+-- (docs/legal/remote-mechanical-wet-signature-precedent.md), the linchpin that
+-- keeps this on the valid side of the forgery/agency line is an EXPLICIT,
+-- per-document authorization from the signer to reproduce their signature in ink
+-- on this specific document.
+--
+-- These columns capture that consent at signing time, alongside the existing
+-- perjury attestation. They are only meaningful for drawn signatures on ink-path
+-- documents (metadata.ink_reproduction = true); other docs leave them false/NULL.
+--
+-- Idempotent.
+
+ALTER TABLE esign_records
+    ADD COLUMN IF NOT EXISTS ink_consent      BOOLEAN DEFAULT FALSE,
+    ADD COLUMN IF NOT EXISTS ink_consent_at   TIMESTAMPTZ,
+    ADD COLUMN IF NOT EXISTS ink_consent_text TEXT;
+
+COMMENT ON COLUMN esign_records.ink_consent IS
+    'TRUE when the signer expressly authorized reproducing their drawn signature '
+    'in ink on this document (pen-plotter path). Captured at signing time.';
+COMMENT ON COLUMN esign_records.ink_consent_at IS
+    'When the ink-reproduction consent was given (signer-side timestamp).';
+COMMENT ON COLUMN esign_records.ink_consent_text IS
+    'Verbatim consent language the signer agreed to (for the audit trail).';