feat: async pipeline, job queue, generation hardening, and docs

feat: enhance AI involvement handling and transparency metrics

deploy: harden inspector + add RAGAS eval harness

refactor: enhance non-invention guard and tier-aware output handling

feat: implement two-layer hallucination grounding check with 21 new tests

- Added support for RICS survey levels (1, 2, 3) in document uploads and reports, allowing for better tier management and retrieval filtering.

- Replaced timezone.utc with UTC from datetime for consistent datetime handling.

fix: comprehensive codebase review fixes (critical + major + minor issues)

fix: apply all bug fixes and improvements (embeddings, cache, postprocess, frontend, tests)

feat: scaffold complete RAG system for RICS-style report generation