M3: Tell me a story flow, LLM settings panel, streamed draft, friendly errors; ADR-017..020

master

Commit

Mrituanjay Nath Jha2d ago

Co-Authored-By: Claude Sonnet 5.5 noreply@anthropic.com Entire-Checkpoint: 01M63PRF2NKZ65K0SPCQ8HBTBN