Fix VibeSec pipeline logic bugs, routing, feedback store, and RLS test cases

feat(scanner): improve precision in auth, rls, and llm rules, add public repo test script

Migrate backend to Gemini 3.1 Flash Lite and optimize JS/TS rulesets

refactor(backend): use asyncio and thread pools for background tasks, optimize scanner AST utils and checks

Refactor scanner layers to use AST architecture, fix uvicorn graceful shutdown

feat(scanner): sync dynamic secrets validation filters and entropy triaging

fix(scanner): resolve base64 file corruption and route classification bugs, sync AST upgrades

feat(hardening): deploy 5 surgical patches resolving TSConfig resolver, platform agnosticism, tenant isolation, SQL RLS Level 2, and LLM noise gate

feat: implement 19-check Moat scanning system to cover all 60 vulnerabilities