chore: remove repo cruft (bd_new, @AGENTS.md)

- Remove bd_new (31MB binary that should never have been tracked)
- Remove @AGENTS.md (duplicate that was already removed but still tracked)
- state.json already in .gitignore and not tracked
- history/EPHEMERAL_MOLECULES_DESIGN.md does not exist

(bd-ov1u)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

@AGENTS.md

@@ -1,40 +0,0 @@
-# Agent Instructions
-
-This project uses **bd** (beads) for issue tracking. Run `bd onboard` to get started.
-
-## Quick Reference
-
-```bash
-bd ready              # Find available work
-bd show <id>          # View issue details
-bd update <id> --status in_progress  # Claim work
-bd close <id>         # Complete work
-bd sync               # Sync with git
-```
-
-## Landing the Plane (Session Completion)
-
-**When ending a work session**, you MUST complete ALL steps below. Work is NOT complete until `git push` succeeds.
-
-**MANDATORY WORKFLOW:**
-
-1. **File issues for remaining work** - Create issues for anything that needs follow-up
-2. **Run quality gates** (if code changed) - Tests, linters, builds
-3. **Update issue status** - Close finished work, update in-progress items
-4. **PUSH TO REMOTE** - This is MANDATORY:
-   ```bash
-   git pull --rebase
-   bd sync
-   git push
-   git status  # MUST show "up to date with origin"
-   ```
-5. **Clean up** - Clear stashes, prune remote branches
-6. **Verify** - All changes committed AND pushed
-7. **Hand off** - Provide context for next session
-
-**CRITICAL RULES:**
-- Work is NOT complete until `git push` succeeds
-- NEVER stop before pushing - that leaves work stranded locally
-- NEVER say "ready to push when you are" - YOU must push
-- If push fails, resolve and retry until it succeeds
-