- Add DraftLetterPanel: collapsible UI below BriefPanel for bills with a
brief; lets users select up to 3 cited points, pick stance/tone, and
generate a plain-text letter via the configured LLM provider
- Stance pre-fills from follow mode (pocket_boost → YES, pocket_veto → NO)
and clears when the user unfollows; recipient derived from bill chamber
- Add POST /api/bills/{bill_id}/draft-letter endpoint with proper LLM
provider/model resolution from AppSetting (respects Settings page choice)
- Add generate_text() to LLMProvider ABC and all four providers
- Expose has_document on BillSchema (list endpoint) via a single batch
query; BillCard shows Brief / Pending / No text indicator per bill
Authored-By: Jack Levy
