Readme Generation

feat: switch frontend to work_sessions; rename passes → conversations throughout

feat: add WorkSession/Conversation types and work_sessions API functions to frontend

feat: add /api/work_sessions router with list, get, categories, timeline, conversations

refactor: move deferred model imports to top-level in queries.py

feat: add get_work_session_conversations query

fix: consolidate DB connections, fix thread params, add token_aggregates optimization

feat: add get_work_session_categories and get_work_session_timeline queries

feat: add list_work_sessions and get_work_session queries

feat: add WorkSession, Conversation, ConversationResponse models

feat: assign sessions to work_sessions during ingestion

feat: add compute_work_date() with 2AM local boundary

feat: add work_sessions table and work_session_id FK to sessions

docs: add work sessions implementation plan

docs: add work sessions design doc (session grouping by project+day)