feat(commit-engine): Enhance console output with rich library

The commit engine now leverages the `rich` library to provide a more visually appealing and informative console experience during various stages of the commit generation and execution process.

*   **New Features**
    *   Integrate the `rich` library for enhanced and structured console output.
    *   Introduce a custom `rich` theme for consistent styling of info, warning, and danger messages.

*   **Enhancements & Refinements**
    *   Display visual feedback with `rich` status spinners during AI message generation and remote push operations.
    *   Present generated commit messages in a formatted `rich` Panel with Markdown rendering for improved readability.
    *   Provide clearer, color-coded `rich` console messages for staging files, dry run completion, overall process completion, and identifying failed groups.
    *   Propagate the `debug` flag to the logger to control console output during debugging sessions, aligning logger and console behavior.

devgen/modules/commit_generator.py

@@ -156,7 +156,7 @@ class CommitEngine:
         template = self.template_env.get_template("commit_message.j2")
         prompt = template.render(group_name=group, diff_text=diff, use_emoji=use_emoji)
 
-        with self.console.status(f"[bold blue]Generating message for {group}...[/bold blue]"):
+        with self.console.status(f"[bold blue]Generating commit message...[/bold blue]"):
             raw = generate_with_ai(
                 prompt,
                 provider=provider,