Implements a new `/core:commit` command that analyzes staged changes to generate a conventional commit message.
The command supports three main modes of operation:
- `/core:commit`: Automatically generates a commit message based on the content of the staged files.
- `/core:commit "custom message"`: Uses the provided string as the full commit message.
- `/core:commit --amend`: Amends the last commit with the new message.
Message generation includes several heuristics:
- **Commit Type:** Determined by file paths (e.g., `_test.go` -> `test`) and diff content (e.g., keywords like `fix` or `refactor`).
- **Scope:** Inferred from the most common directory name among the staged files.
- **Summary:** Extracted from function or class names in the diff, or defaults to a file-based summary.
- **Co-Author:** A `Co-Authored-By` trailer is automatically appended.
This feature streamlines the development workflow by automating the creation of descriptive and conventional commit messages.
