fix(polecat): kill orphan sessions and clear stale hooks during allocation (#448)

ReconcilePool now detects and kills orphan tmux sessions (sessions without
corresponding polecat directories). This prevents allocation from being
blocked by broken state from crashed polecats.

Changes:
- Add tmux to Manager to check for orphan sessions during reconciliation
- Add ReconcilePoolWith for testable session/directory reconciliation logic
- Always clear hook_bead slot when reopening agent beads (fixes stale hooks)
- Prune stale git worktree entries during reconciliation

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/start.go

@@ -682,7 +682,7 @@ func cleanupPolecats(townRoot string) {
 
 	for _, r := range rigs {
 		polecatGit := git.NewGit(r.Path)
-		polecatMgr := polecat.NewManager(r, polecatGit)
+		polecatMgr := polecat.NewManager(r, polecatGit, nil) // nil tmux: just listing, not allocating
 
 		polecats, err := polecatMgr.List()
 		if err != nil {