fix: Extract lib/worktree.sh — create, recover, cleanup (#797)

Extract reusable worktree management into lib/worktree.sh:
- worktree_create: git worktree add + checkout + submodules
- worktree_recover: detect existing worktree, reuse or recreate
- worktree_cleanup: remove worktree + clear Claude Code project cache
- worktree_cleanup_stale: scan /tmp for orphaned worktrees, skip preserved
- worktree_preserve: mark worktree for debugging (skip stale cleanup)

Update callers:
- dev-agent.sh: use worktree_create/worktree_recover/worktree_cleanup
- action-agent.sh: use worktree_cleanup/worktree_preserve
- formula-session.sh: delegate cleanup_stale_crashed_worktrees, use worktree_preserve
- All formula agents source lib/worktree.sh

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -24,7 +24,7 @@ disinto/                 (code repo)
 │                  supervisor-poll.sh — legacy bash orchestrator (superseded)
 ├── vault/         vault-poll.sh, vault-agent.sh, vault-fire.sh — action gating + procurement
 ├── action/        action-poll.sh, action-agent.sh — operational task execution
-├── lib/           env.sh, agent-session.sh, ci-helpers.sh, ci-debug.sh, load-project.sh, parse-deps.sh, guard.sh, mirrors.sh, pr-lifecycle.sh, issue-lifecycle.sh, build-graph.py
+├── lib/           env.sh, agent-session.sh, ci-helpers.sh, ci-debug.sh, load-project.sh, parse-deps.sh, guard.sh, mirrors.sh, pr-lifecycle.sh, issue-lifecycle.sh, worktree.sh, build-graph.py
 ├── projects/      *.toml.example — templates; *.toml — local per-box config (gitignored)
 ├── formulas/      Issue templates (TOML specs for multi-step agent tasks)
 └── docs/          Protocol docs (PHASE-PROTOCOL.md, EVIDENCE-ARCHITECTURE.md)