feat(phase2+3): DI container, plugins, PII sanitizer, tool policy, audit log, cache invalidation, ARIA, CSS vars

Phase 2 — Architecture & Quality:
- A-5: DI container (src/lib/container.ts)
- L-6: Prompt versioning (src/lib/db/prompts.ts)
- L-7: Eval scheduler (src/lib/evals/scheduler.ts)
- L-8: Plugin architecture (src/lib/plugins/index.ts)
- T-3: Integration tests (42 tests, 9 suites)

Phase 3 — UX & Polish:
- P-1: 500 error page (src/app/error.tsx)
- P-2: Audit log viewer (dashboard/audit-log/page.tsx)
- U-2: ARIA attributes on error pages
- U-5: Typed global-error.tsx params
- U-6: CSS variables for accent/semantic/traffic colors
- L-3: Output PII sanitization (src/lib/piiSanitizer.ts)
- L-4: Tool-calling allowlist/denylist (src/lib/toolPolicy.ts)
- L-9: Semantic cache invalidation API + auto-cleanup
- D-5: SECURITY.md updated to v1.0.x
- F-2: Deleted .env copy

SECURITY.md

@@ -20,9 +20,9 @@ If you discover a security vulnerability in OmniRoute, please report it responsi
 
 | Version | Support Status |
 | ------- | -------------- |
-| 0.8.x   | ✅ Active      |
-| 0.7.x   | ✅ Security    |
-| < 0.7.0 | ❌ Unsupported |
+| 1.0.x   | ✅ Active      |
+| 0.8.x   | ✅ Security    |
+| < 0.8.0 | ❌ Unsupported |
 
 ---