feat(devgen/modules): enhance changelog and license generation with improved file handling

This update introduces improvements to the changelog generator's file handling logic, including proper prepending of new entries and automatic header management. It also refines the license generator's template directory structure and cleans up minor formatting issues in the commit generator.

**New Features**
- Added intelligent changelog prepending logic that preserves existing headers and maintains proper formatting when updating files
- Implemented automatic `# CHANGELOG` header insertion for new changelog files

**Enhancements & Refinements**
- Changed changelog version headers from `#` to `##` for better markdown hierarchy
- Updated license generator to use `templates/licenses` directory instead of `prompt_templates/licenses`
- Removed unnecessary whitespace and improved code formatting in commit generator
- Enhanced changelog file writing logic to handle both new and existing files more robustly
```

devgen/modules/changelog_generator.py

@@ -120,7 +120,7 @@ class ChangelogGenerator:
     ) -> str:
         """Generates markdown changelog from parsed commits."""
         date_str = datetime.now().strftime("%Y-%m-%d")
-        md = [f"# {version} ({date_str})\n"]
+        md = [f"## {version} ({date_str})\n"]
 
         # Order: Breaking, Features, Fixes, Docs, Others
         order = [
@@ -163,14 +163,19 @@ class ChangelogGenerator:
 
         if output_file:
             path = Path(output_file)
-            # If file exists, prepend? For now, just overwrite or append logic could be complex.
-            # Let's implement prepend logic if file exists.
             if path.exists():
                 old_content = path.read_text(encoding="utf-8")
-                new_content = old_content + "\n\n" + md_content
+                # Prepend the new content, assume # CHANGELOG is at the top or needs to be
+                if old_content.strip().startswith("# CHANGELOG"):
+                    lines = old_content.split("\n", 1)
+                    header = lines[0]
+                    rest = lines[1] if len(lines) > 1 else ""
+                    new_content = f"{header}\n\n{md_content}\n{rest.lstrip()}"
+                else:
+                    new_content = f"# CHANGELOG\n\n{md_content}\n\n{old_content}"
                 path.write_text(new_content, encoding="utf-8")
             else:
-                path.write_text(md_content, encoding="utf-8")
+                path.write_text(f"# CHANGELOG\n\n{md_content}", encoding="utf-8")
 
             self.logger.info(f"Changelog written to {output_file}")
             print(f" Changelog updated: {output_file}")

devgen/modules/commit_generator.py

@@ -39,7 +39,6 @@ IGNORE_PATTERNS = [
 ]
 
 
-
 class CommitEngine:
     """
     Engine for generating AI-powered commit messages.
@@ -98,11 +97,11 @@ class CommitEngine:
                 ]
             )
             files = [f.strip() for f in out.split("\n") if f.strip()]
-            
+
             # Also get staged files (in case of a previous failed run)
             staged_out = run_git_command(["git", "diff", "--name-only", "--cached"])
             staged_files = [f.strip() for f in staged_out.split("\n") if f.strip()]
-            
+
             # Combine and deduplicate
             all_files = list(set(files + staged_files))
             return all_files

devgen/modules/license_generator.py

@@ -8,9 +8,7 @@ class LicenseGenerator:
     """Generates license files from templates."""
 
     def __init__(self):
-        self.templates_dir = (
-            Path(__file__).parent.parent / "prompt_templates" / "licenses"
-        )
+        self.templates_dir = Path(__file__).parent.parent / "templates" / "licenses"
 
     def list_licenses(self) -> List[Dict[str, str]]:
         """Lists available license templates."""