chore: sync generated registry files for v4.3.0

- Updated catalog to 614 skills
- Updated README.md with correct skill counts
- Updated package.json to version 4.3.0
- Added release notes for v4.3.0
- Updated SOURCES.md with new attributions

package.json

@@ -1,7 +1,7 @@
 {
   "name": "antigravity-awesome-skills",
-  "version": "4.2.0",
-  "description": "560+ agentic skills for Claude Code, Gemini CLI, Cursor, Antigravity & more. Installer CLI.",
+  "version": "4.3.0",
+  "description": "614+ agentic skills for Claude Code, Gemini CLI, Cursor, Antigravity & more. Installer CLI.",
   "license": "MIT",
   "scripts": {
     "validate": "python3 scripts/validate_skills.py",