Second Brain agent integration complete

## What We Built
Set up Second Brain integration for all agents.

## Components
- API keys generated for: bob, kai, atlas, sage, maya
- Keys stored in ~/.brain-keys (gitignored, chmod 600)
- BRAIN.md created with trigger rules and payload formats
- AGENTS.md updated with Second Brain section

## Trigger Rules
Save immediately:
- Decisions made
- Specs finalized
- Research completed
- Lessons learned

Save at end of work:
- Features completed
- Tasks with context
- Important conversations

## API
- POST https://brain.widerwings.com/api/memories
- Auth: Bearer token
- Auto-vectorizes with OpenAI text-embedding-3-small
- Semantic search via match_memories RPC