feat(polecat): add repo path to worktrees for LLM ergonomics (GH#283)

Changes polecat worktree structure from:
  polecats/<name>/
to:
  polecats/<name>/<rigname>/

This gives Claude Code agents a recognizable directory name (e.g., tidepool/)
in their cwd instead of just the polecat name, preventing confusion about
which repo they are working in.

Key changes:
- Add clonePath() method to manager.go and session_manager.go for the actual
  git worktree path, keeping polecatDir() for existence checks
- Update Add(), RepairWorktree(), Remove() to use new structure
- Update daemon lifecycle and restart code for new paths
- Update witness handlers to detect both structures
- Update doctor checks (rig_check, branch_check, config_check,
  claude_settings_check) for backward compatibility
- All code includes fallback to old structure for existing polecats

Fixes #283

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

internal/doctor/branch_check.go

@@ -468,12 +468,20 @@ func (c *CloneDivergenceCheck) findAllClones(townRoot string) []string {
 			}
 		}
 
-		// Add polecats
+		// Add polecats (handle both new and old structures)
+		// New structure: polecats/<name>/<rigname>/
+		// Old structure: polecats/<name>/
+		rigName := entry.Name()
 		polecatsPath := filepath.Join(rigPath, "polecats")
 		if polecatEntries, err := os.ReadDir(polecatsPath); err == nil {
 			for _, polecat := range polecatEntries {
 				if polecat.IsDir() && !strings.HasPrefix(polecat.Name(), ".") {
-					path := filepath.Join(polecatsPath, polecat.Name())
+					// Try new structure first
+					path := filepath.Join(polecatsPath, polecat.Name(), rigName)
+					if !c.isGitRepo(path) {
+						// Fall back to old structure
+						path = filepath.Join(polecatsPath, polecat.Name())
+					}
 					if c.isGitRepo(path) {
 						clones = append(clones, path)
 					}