Add skip property to file_item.py to support conditional file creation (#20)

### Overview
This PR introduces a `skip` property to the `file_item.py` module,
enabling the option to bypass file creation based on conditional
settings.

### Changes
- **Added `skip` property**: The constructor now initializes the `skip`
property based on input properties, defaulting to `False` if not
specified.
- **Conditional file creation**: Modified the `create` method to check
the `skip` property. When set to `True`, the process logs that file
creation is skipped and exits early.

### Justification
The ability to conditionally skip file creation is essential for
workflows that require selective file management. This update allows
greater control over file generation without altering existing logic.

### Impact
This enhancement reduces unnecessary file creation, optimizing resource
use, especially in large projects or in cases where specific files are
conditionally excluded. No breaking changes are introduced, ensuring
compatibility with existing workflows.

Author: httpdss

example/structure.yaml

@@ -1,5 +1,6 @@
 structure:
   - README.md:
+      skip: true
       content: |
         # {{@ project_name @}}
         This is a template repository.

struct_module/commands/validate.py

@@ -46,7 +46,7 @@ def _validate_folders_config(self, folders):
               raise ValueError(f"The content of '{name}' must be a dictionary.")
             if 'struct' not in content:
               raise ValueError(f"Dictionary item '{name}' must contain a 'struct' key.")
-            if not isinstance(content['struct'], str):
+            if not isinstance(content['struct'], str) and not isinstance(content['struct'], list):
               raise ValueError(f"The 'struct' value for '{name}' must be a string.")
 
 
@@ -104,7 +104,8 @@ def _validate_structure_config(self, structure):
               # Check if 'prompt' key is present and its value is a string
               if 'prompt' in content and not isinstance(content['prompt'], str):
                 raise ValueError(f"The 'prompt' value for '{name}' must be a string.")
-              # Check if 'prompt' key is present but no OpenAI API key is found
+              if 'skip' in content and not isinstance(content['skip'], bool):
+                raise ValueError(f"The 'skip' value for '{name}' must be a string.")
             elif not isinstance(content, str):
               raise ValueError(f"The content of '{name}' must be a string or dictionary.")
       self.logger.info("Configuration validation passed.")

struct_module/file_item.py

@@ -23,6 +23,7 @@ def __init__(self, properties):
       self.content_location = properties.get("file")
       self.permissions = properties.get("permissions")
       self.input_store = properties.get("input_store")
+      self.skip = properties.get("skip", False)
 
       self.system_prompt = properties.get("system_prompt") or properties.get("global_system_prompt")
       self.user_prompt = properties.get("user_prompt")
@@ -118,6 +119,11 @@ def apply_template_variables(self, template_vars):
 
     def create(self, base_path, dry_run=False, backup_path=None, file_strategy='overwrite'):
       file_path = os.path.join(base_path, self.name)
+
+      if self.skip:
+        self.logger.info(f"Skipping file creation: {file_path}")
+        return
+
       if dry_run:
         self.logger.info(f"[DRY RUN] Would create file: {file_path} with content: \n\n{self.content}")
         return