Add initial implementation of gitea-mcp-forward-auth microservice

- Create build and release workflows for CI/CD
- Implement Dockerfile for multi-stage builds
- Add core authentication logic with token validation
- Include HTTP handler for authorization checks
- Set up Kubernetes deployment and service manifests
- Update README with usage instructions and configuration details

deploy/k3s/service.yaml

@@ -0,0 +1,15 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: gitea-mcp-auth-proxy
+  labels:
+    app: gitea-mcp-auth-proxy
+spec:
+  selector:
+    app: gitea-mcp-auth-proxy
+  ports:
+    - name: http
+      port: 80
+      targetPort: http
+      protocol: TCP
+  type: ClusterIP