Fix gt doctor hanging on large workspaces

Two fixes:

1. FindAllLocks in lock/lock.go was walking into massive git repo
   clones (e.g., 13GB java repos in crew members). Added skipDirs map
   to skip .git, node_modules, vendor, target, build, and other large
   irrelevant directories during filepath.Walk.

2. CloneDivergenceCheck's git fetch could hang indefinitely waiting
   for SSH authentication prompts. Added environment variables to
   disable interactive SSH features:
   - GIT_SSH_COMMAND='ssh -o BatchMode=yes -o ConnectTimeout=3'
   - GIT_TERMINAL_PROMPT=0

Doctor now completes in ~2 minutes instead of hanging indefinitely.

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

internal/lock/lock.go

@@ -28,10 +28,10 @@ var (
 
 // LockInfo contains information about who holds a lock.
 type LockInfo struct {
-	PID       int       `json:"pid"`
+	PID        int       `json:"pid"`
 	AcquiredAt time.Time `json:"acquired_at"`
-	SessionID string    `json:"session_id,omitempty"`
-	Hostname  string    `json:"hostname,omitempty"`
+	SessionID  string    `json:"session_id,omitempty"`
+	Hostname   string    `json:"hostname,omitempty"`
 }
 
 // IsStale checks if the lock is stale (owning process is dead).
@@ -194,15 +194,34 @@ func (l *Lock) write(sessionID string) error {
 
 // FindAllLocks scans a directory tree for agent.lock files.
 // Returns a map of worker directory -> LockInfo.
+// Skips .git directories and other large irrelevant directories for performance.
 func FindAllLocks(root string) (map[string]*LockInfo, error) {
 	locks := make(map[string]*LockInfo)
 
+	// Directories to skip during walk (these won't contain .runtime/agent.lock files)
+	skipDirs := map[string]bool{
+		".git":         true,
+		"node_modules": true,
+		"vendor":       true,
+		"target":       true, // Rust/Java build output
+		"build":        true,
+		"dist":         true,
+		".gradle":      true,
+		".m2":          true,
+		"bazel-out":    true,
+		"bazel-bin":    true,
+	}
+
 	err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return nil // Skip errors
 		}
 
 		if info.IsDir() {
+			// Skip irrelevant directories for performance
+			if skipDirs[info.Name()] {
+				return filepath.SkipDir
+			}
 			return nil
 		}