feat: initialize project structure and dependencies

- Initialize Go module with all required dependencies
- Add Makefile with build targets (all, frontend, build, clean, test, run, build-linux, build-windows)
- Create main.go skeleton with CLI flags (--addr, --data, --init)
- Add README.md with project overview and usage instructions
- Add .gitignore for bin, data, and build artifacts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -0,0 +1,33 @@
+# GitM - Gitea Repository Sync Tool
+
+Cross-platform tool to synchronize all repositories from multiple Gitea servers to local storage.
+
+## Features
+
+- Single binary deployment
+- Web UI for management (Vue 3 + Element Plus)
+- SQLite database
+- JWT authentication
+- Scheduled and manual sync
+- Cross-platform (Windows, Linux)
+
+## Build
+
+```bash
+make all
+```
+
+## Run
+
+```bash
+./bin/gitm --init
+./bin/gitm
+./bin/gitm --addr :9090
+```
+
+## Development
+
+```bash
+cd web && npm install && npm run dev
+go run main.go
+```