refactor: adopt PathRegistry in worker config

Update internal/worker/config.go to use centralized PathRegistry:

Changes:
- Initialize PathRegistry with config.FromEnv() in LoadConfig
- Update BasePath default to use paths.ExperimentsDir()
- Update DataDir default to use paths.DataDir()
- Simplify DataDir logic by using PathRegistry directly

Benefits:
- Consistent directory locations via PathRegistry
- Centralized path management across worker and api-server
- Simpler configuration with fewer conditional branches

internal/worker/config.go

@@ -147,6 +147,9 @@ func LoadConfig(path string) (*Config, error) {
 	// Get smart defaults for current environment
 	smart := config.GetSmartDefaults()
 
+	// Use PathRegistry for consistent path management
+	paths := config.FromEnv()
+
 	if cfg.Port == 0 {
 		cfg.Port = config.DefaultSSHPort
 	}
@@ -158,11 +161,8 @@ func LoadConfig(path string) (*Config, error) {
 		cfg.Host = host
 	}
 	if cfg.BasePath == "" {
-		basePath, err := smart.BasePath()
-		if err != nil {
-			return nil, fmt.Errorf("failed to get default base path: %w", err)
-		}
-		cfg.BasePath = basePath
+		// Prefer PathRegistry over smart defaults for consistency
+		cfg.BasePath = paths.ExperimentsDir()
 	}
 	if cfg.RedisAddr == "" {
 		redisAddr, err := smart.RedisAddr()
@@ -203,15 +203,8 @@ func LoadConfig(path string) (*Config, error) {
 		cfg.DataManagerPath = "./data_manager"
 	}
 	if cfg.DataDir == "" {
-		if cfg.Host == "" || !cfg.AutoFetchData {
-			cfg.DataDir = config.DefaultLocalDataDir
-		} else {
-			dataDir, err := smart.DataDir()
-			if err != nil {
-				return nil, fmt.Errorf("failed to get default data directory: %w", err)
-			}
-			cfg.DataDir = dataDir
-		}
+		// Use PathRegistry for consistent data directory
+		cfg.DataDir = paths.DataDir()
 	}
 	if cfg.SnapshotStore.Timeout == 0 {
 		cfg.SnapshotStore.Timeout = 10 * time.Minute