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- W6.attach: fixed outdated CLAUDE.md claim — threshold banner is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/users.ts

@@ -314,6 +314,11 @@ export const userPermissionOverrides = pgTable(
     id: text('id')
       .primaryKey()
       .$defaultFn(() => crypto.randomUUID()),
+    // onDelete: 'cascade' is intentional here (not 'set null' as a stale 2026-05-12
+    // audit item suggested). A permission override has no semantic value without
+    // the user it grants permissions to — preserving a row with user_id=NULL
+    // would be an orphan with no audit value, since the override is per-user
+    // additive permissions, not a historical event we need to retain.
     userId: text('user_id')
       .notNull()
       .references(() => user.id, { onDelete: 'cascade' }),