feat: ACN Application Security Standard V7.30 compliance (19/23 items)

CRITICAL — Authentication & Access:
- TOTP MFA: otpauth-based, QR setup UI, sign-in flow integration,
  admin disable override, /account/security self-service page
- Session Timeouts: 8h absolute (maxAge), 30min idle (updateAge)
- Failed Auth Logging: Pino warn for invalid password/user/totp,
  info for successful login, audit entries for all auth events
- Concurrent Session Limit: ActiveSession model, oldest-kick strategy,
  max 3 per user (configurable in SystemSettings)

CRITICAL — HTTP Security:
- HSTS: max-age=31536000; includeSubDomains
- CSP: script/style/img/font/connect-src with Gemini/OpenAI whitelist
- X-XSS-Protection: 0 (CSP replaces legacy)
- Auth page cache: no-store, no-cache, must-revalidate
- Rate Limiting: 100/15min general API, 5/15min auth (Map-based)

Data Protection:
- XSS Sanitization: DOMPurify on comment bodies
- autocomplete="new-password" on all password/secret fields
- SameSite=Strict on all cookies (Credentials-only, no OAuth)
- File Upload Magic Bytes validation (PNG/JPEG/WebP/GIF/BMP/TIFF)

Logging & Monitoring:
- Login/Logout audit entries (Auth entityType)
- External API call logging with timing (OpenAI, Gemini)
- Input validation failure logging at warn level
- Concurrent session tracking in ActiveSession table

Documentation:
- docs/security-architecture.md (11 sections)
- docs/sdlc.md (CI pipeline, security gates, incident response)
- .gitea/PULL_REQUEST_TEMPLATE.md (security checklist)

Schema: User.totpSecret/totpEnabled, SystemSettings.sessionMaxAge/
sessionIdleTimeout/maxConcurrentSessions, ActiveSession model

Tests: 310 engine + 37 staffing pass. TypeScript clean.

Co-Authored-By: claude-flow <ruv@ruv.net>

.gitea/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,22 @@
+## Summary
+
+<!-- Brief description of the changes -->
+
+## Security Checklist
+
+- [ ] No secrets in code (API keys, passwords, tokens)
+- [ ] Input validation (Zod schema) on new endpoints
+- [ ] Audit logging for data mutations (`createAuditEntry`)
+- [ ] No SQL injection risk (Prisma ORM used, no raw queries)
+- [ ] XSS prevention (user-provided text properly escaped/sanitized)
+- [ ] RBAC permission check on new procedures (`requirePermission`)
+- [ ] No new dependencies with known vulnerabilities (`pnpm audit`)
+
+## Test Plan
+
+<!-- How was this tested? -->
+
+- [ ] Unit tests pass (`pnpm test:unit`)
+- [ ] TypeScript compiles (`tsc --noEmit`)
+- [ ] Linting passes (`pnpm lint`)
+- [ ] Manual testing performed