Squad setup: open PR to land .squad/ team init on main

[dfberry]

Problem

Branch protection on main requires PRs — the squad setup commit (8a072d6) was rejected on direct push.

What needs to happen

1. Create a branch from the current main HEAD
2. Cherry-pick or reset with commit 8a072d6 (squad team init)
3. Open a PR targeting main
4. Merge once CI passes

Files in the commit

• .squad/ directory (all team files, charters, casting, routing)
• .gitattributes (union merge driver for .squad/ state)
• .github/agents/squad.agent.md
• .github/workflows/squad-*.yml

Notes

The commit is currently only on the local main branch, ahead of origin by 1.
Kaylee should handle the branch/PR mechanics.