chore: Remove commit-message-generator skill definition file

- Remove SKILL.md as the commit message generation functionality is now integrated into the standard workflow
- Commit message suggestions can be generated directly during development without separate skill configuration

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/skills/commit-message-generator/SKILL.md

@@ -1,33 +0,0 @@
----
-name: commit-message-generator
-description: Generate appropriate commit messages based on Git diffs
----
-
-## Prerequisites
-- This Skill retrieves Git diffs and suggests meaningful commit messages
-- Message format should follow Conventional Commits
-- Commit messages should have a one-line Conventional Commits header, an optional blank second line, and from the third line onward include a bulleted list summarizing the changes
-- Commit messages should be in English
-- **Never perform Git commit or Git push**
-
-## Steps
-1. Run `git status` to check modified files
-2. Retrieve diffs with `git diff` or `git diff --cached`
-3. Analyze the diff content and determine if changes should be split into multiple commits
-4. For each logical group of changes:
-   - List the target files
-   - Generate a message in English compliant with Conventional Commits
-   - Suggest the command: `git add <files> && git commit -m "<message>"`
-5. If changes are extensive and should be split, provide:
-   - Rationale for the split
-   - Multiple commit suggestions with their respective target files and messages
-
-## Commit Splitting Guidelines
-- Split commits when changes span multiple logical concerns (e.g., feature + refactoring)
-- Group related files that serve the same purpose
-- Keep each commit focused on a single, atomic change
-
-## Notes
-- **This Skill must never execute `git commit` or `git push`**
-- Only suggest commands; execution is entirely at user's discretion
-- Users must explicitly perform commits and pushes themselves