Add initial project setup with Bun, including .gitignore, package.json, and TypeScript configuration

- Created .gitignore to exclude common build and dependency files.
- Added package.json for project metadata and dependencies.
- Introduced tsconfig.json for TypeScript compiler options.
- Included bun.lock for dependency locking.
- Added CLAUDE.md for project documentation.
- Set up Gitea workflow for Claude Assistant integration.

package.json

@@ -0,0 +1,10 @@
+{
+  "name": "backend",
+  "type": "module",
+  "devDependencies": {
+    "@types/bun": "latest"
+  },
+  "peerDependencies": {
+    "typescript": "^5"
+  }
+}