fix: Fix Ruff PERF403 and add cache_dir validator

- Convert dictionary comprehension in setup.py to fix PERF403
- Add cache_dir validator to normalize paths like config_dir
- Follows CodeRabbit review feedback

src/backend/base/langflow/initial_setup/setup.py

@@ -62,10 +62,11 @@ from langflow.services.deps import (
 
 def update_projects_components_with_latest_component_versions(project_data, all_types_dict):
     # Flatten the all_types_dict for easy access
-    all_types_dict_flat = {}
-    for category in all_types_dict.values():
-        for key, component in category.items():
-            all_types_dict_flat[key] = component
+    all_types_dict_flat = {
+        key: component
+        for category in all_types_dict.values()
+        for key, component in category.items()
+    }
 
     node_changes_log = defaultdict(list)
     project_data_copy = deepcopy(project_data)

src/lfx/src/lfx/services/settings/base.py

@@ -509,6 +509,26 @@ class Settings(BaseSettings):
 
         return str(value)
 
+    @field_validator("cache_dir", mode="before")
+    @classmethod
+    def validate_cache_dir(cls, value):
+        """Validate and normalize cache_dir path.
+
+        If not set, returns None and the factory will fall back to config_dir.
+        If set, resolves to an absolute path and creates the directory if needed.
+        """
+        if not value:
+            return None
+
+        if isinstance(value, str):
+            value = Path(value)
+        # Resolve to absolute path to handle relative paths correctly
+        value = value.resolve()
+        if not value.exists():
+            value.mkdir(parents=True, exist_ok=True)
+
+        return str(value)
+
     @field_validator("database_url", mode="before")
     @classmethod
     def set_database_url(cls, value, info):