Reorganize: Move all skills to skills/ folder

- Created skills/ directory
- Moved 272 skills to skills/ subfolder
- Kept agents/ at root level
- Kept installation scripts and docs at root level

Repository structure:
- skills/           - All 272 skills from skills.sh
- agents/           - Agent definitions
- *.sh, *.ps1       - Installation scripts
- README.md, etc.   - Documentation

Co-Authored-By: Claude <noreply@anthropic.com>

skills/plugins/claude-code-safety-net/sgconfig.yml

@@ -0,0 +1,6 @@
+ruleDirs:
+- ast-grep/rules
+testConfigs:
+- testDir: ast-grep/rule-tests
+utilDirs:
+- ast-grep/utils