feat(daemons): implement discovery and list command (bd-146, bd-147)

- Add daemon discovery mechanism with socket scanning
- Implement depth-limited filesystem walk to avoid hangs
- Add DaemonInfo struct with metadata collection
- Create 'bd daemons list' command with table and JSON output
- Add FindDaemonByWorkspace and CleanupStaleSockets utilities
- Fix workspace path to be parent of .beads directory
- Add comprehensive tests for discovery functionality

Closes bd-146
Closes bd-147

cmd/bd/daemon.go

@@ -1079,8 +1079,11 @@ func runDaemonLoop(interval time.Duration, autoCommit, autoPush bool, logPath, p
 	defer func() { _ = store.Close() }()
 	log.log("Database opened: %s", daemonDBPath)
 
-	workspacePath := filepath.Dir(daemonDBPath)
-	socketPath := filepath.Join(workspacePath, "bd.sock")
+	// Get workspace path (.beads directory)
+	beadsDir := filepath.Dir(daemonDBPath)
+	// Get actual workspace root (parent of .beads)
+	workspacePath := filepath.Dir(beadsDir)
+	socketPath := filepath.Join(beadsDir, "bd.sock")
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()