feat(audit-cleanup): finish all 15 outstanding items from verified backlog

Audit cleanup completion plan, all tiers shipped:

Tier 1 (security + data integrity)
- A.7 RTBF true wipe: redact email_messages body/subject/addresses for
  threads owned by deleted client; redact document_sends.recipient_email;
  collect file storage keys + delete blobs post-commit.
- A.8 user_permission_overrides FK: documented inline why cascade is
  correct (not set-null as audit suggested) — overrides have no value
  without their user.
- W2.14 PII redaction: camelCase normalization in audit.ts +
  error-events.service.ts isSensitiveKey; added city/postal/country/
  birth fragments. firstName/lastName/dateOfBirth/postalCode etc. now
  caught in BOTH masker paths. 12 new test cases lock the coverage.

Tier 2 (Documenso completion + refactor)
- C.2: documentEvents.recipient_email column + partial unique index for
  per-recipient webhook dedup (migration 0075). handleDocumentSigned
  now sets recipient_email on insert.
- Phase 2: completion_cc_emails distribution. handleDocumentCompleted
  reads documents.completionCcEmails, filters out signer-duplicates
  case-insensitively, fans signed PDF out to non-signer recipients.
- C.4: extracted createPublicInterest() service from the 346-line
  api/public/interests route. Route becomes a thin shell (rate-limit,
  port resolution, audit log, email fan-out). The trio creation logic
  is now unit-testable without an HTTP fixture.
- Phase 4: POST /api/v1/document-templates/[id]/detect-fields wired
  to document-field-detector.detectFields(). Sparkles "Auto-detect"
  button added to template-editor.tsx — maps DetectedField → marker
  with best-guess merge token (DATE / NAME / EMAIL); user retags.

Tier 3 (reporting + recommender snapshot lockfiles)
- W7.reports: extracted rollupStageRevenue / rollupStageCounts /
  computeTotalForecast / computeOccupancyRate / rollupBerthStatusCounts
  into src/lib/services/report-math.ts (pure functions). 16 new tests
  including an inline-snapshot lockfile on a representative 7-stage
  forecast. report-generators.ts now delegates.
- W7.recommender: 18 new toMatchSnapshot tripwires on classifyTier
  boundaries + computeHeat at canonical input points.

Tier 4 (rolling)
- W6.attach: fixed outdated CLAUDE.md claim — threshold banner is
  informational and never depended on IMAP; bounce monitoring (the
  IMAP poller) is separate.
- D.1 + D.2: documented deferral inline with full why-not-build-it
  reasoning so a future engineer sees the rationale.
- G.1: representative formatDate sweep (audit-log-list, user-list,
  document-templates merge tokens, document-signing email). Rest of
  the ~100 sites stay rolling.

Quality gates: 1420/1420 vitest (46 new tests above baseline of 1374),
tsc clean, 0 lint errors.

Plan: docs/superpowers/plans/2026-05-18-audit-cleanup-completion.md
Migration: 0075_c2_document_events_recipient_email.sql (applied to dev DB).

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

src/lib/db/schema/documents.ts

@@ -207,8 +207,13 @@ export const documentEvents = pgTable(
     // H-01: events outlive their signer row so the audit trail stays
     // intact if a recipient is removed.
     signerId: text('signer_id').references(() => documentSigners.id, { onDelete: 'set null' }),
+    // C.2: recipient_email captured at event time. Enables per-recipient
+    // dedup (`(documenso_document_id, recipient_email, event_type)`) so
+    // a RECIPIENT_SIGNED webhook for signer-A doesn't dedup against an
+    // earlier RECIPIENT_SIGNED for signer-B on the same envelope.
+    recipientEmail: text('recipient_email'),
     eventData: jsonb('event_data').default({}),
-    signatureHash: text('signature_hash'), // deduplication
+    signatureHash: text('signature_hash'), // deduplication (legacy: per-payload-hash)
     createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
   },
   (table) => [
@@ -218,6 +223,13 @@ export const documentEvents = pgTable(
     uniqueIndex('idx_de_dedup')
       .on(table.documentId, table.signatureHash)
       .where(sql`${table.signatureHash} IS NOT NULL`),
+    // C.2: per-recipient event dedup. Distinct event_type per (document,
+    // recipient) so re-delivery of the same SIGNED webhook for the same
+    // recipient is a no-op, while a different recipient's SIGNED still
+    // lands.
+    uniqueIndex('idx_de_per_recipient_dedup')
+      .on(table.documentId, table.recipientEmail, table.eventType)
+      .where(sql`${table.recipientEmail} IS NOT NULL`),
   ],
 );