Merge: Restore root-level structure + add skills/docs/codebases

- Restored original root-level src/, package.json, etc.
- Added skills/ directory with Claude Code skills
- Added original-docs/ with source documentation
- Added codebases/z-ai-tooling/ as reference codebase
- Updated README.md with complete documentation

Total: Combined 82 original files + new skills structure

codebases/z-ai-tooling/postcss.config.mjs

@@ -0,0 +1,5 @@
+const config = {
+  plugins: ["@tailwindcss/postcss"],
+};
+
+export default config;