feat: Phase 3 — audit log, analysis history API, evidence_id in UI

Fix: add GitHub Pages and HF Space to default CORS origins

Fix: Add ALLOWED_DOC_TYPES and use tuples for type validation

Fix: Add ALLOWED_DOC_TYPES to Settings

Fix: Change sets to tuples to support concatenation

Fix: Add ALLOWED_VIDEO_TYPES to Settings (empty set)

Fix: Add missing Set import to config.py

Fix: Add ALLOWED_IMAGE_TYPES and ALLOWED_UPLOAD_EXTENSIONS to Settings

Config: Update production configuration with environment variables

Refactor cache methods to accept file identifier types

Add model caching infrastructure (#35)

Add architecture hardening: rate limiting, caching, and CI/CD (#14)

Add file validation utility (#4)

Add centralized logging configuration

Add backend configuration system (#1)

Initial commit: Project structure and documentation