Refactor: Modularized codebase and consolidated Oracle bridges

Sage 6.5: Transform into lean text-only agent, remove RAG/Voice/Mongo, optimize model loading, and extend UI/Logic verification tests

fix: agent history integration, OOM protection, and UI cleanup

feat: remove MongoDB and Sacred Knowledge tab, add agent welcome message, fix typos

refactor: Pass model_size explicitly (1b for HF, 4b for Local) instead of using ENV

refactor: Modularize app structure (app_module.py + thin entry points)

chore: Prepare app.py for HF Spaces (remove SSL/share), keep local config in app_local.py