Second Brain UI: Added project and agent filters

What

Added filter dropdowns to all memory listing pages in Second Brain web UI.

Pages Updated

• /memories (main listing)
• /specs
• /conversations
• /decisions
• /research
• /tasks
• /context (NEW page)

Filters Added

1. Project filter: MedSchools.ai, WiderWings, Second Brain, Operations
2. Agent filter: Shows name + role (e.g. "Bob (Chief of Staff)")

Technical Details

• Added brain_agents to Supabase types
• Each page.server.ts loads agents list
• Filters by created_by and project_id fields
• Agent dropdown shows description field for role

Commits

• 8d16e4a: Added project+agent filters
• 50fe088: Added Context page + agent roles in dropdowns