**chore(docs):** add .gitignore for docs and introduce bun.lock file

- Add `.gitignore` to exclude `node_modules/`, `.vitepress/cache/`, and `.vitepress/dist/` directories
- Include `bun.lock` for dependency management with Bun

CONTRIBUTING.md

@@ -0,0 +1,117 @@
+# Contributing
+
+Thank you for your interest in contributing to DIUN Webhook Dashboard!
+
+## Prerequisites
+
+- [Go 1.26+](https://go.dev/dl/)
+- [Bun](https://bun.sh/) (frontend package manager and runtime)
+
+## Project Structure
+
+```
+cmd/diunwebhook/       — main application entrypoint
+pkg/diunwebhook/       — core library (handlers, DB, models)
+frontend/              — React SPA (Bun + Vite + React 19 + Tailwind + shadcn/ui)
+docs/                  — VitePress documentation site
+.gitea/workflows/      — CI/CD workflows (Gitea Actions)
+Dockerfile             — 3-stage multi-stage build
+compose.yml            — deploy compose (pulls from Gitea registry)
+compose.dev.yml        — dev compose (builds locally)
+```
+
+## Development Setup
+
+### Backend
+
+Start the Go server (serves on `:8080` by default):
+
+```bash
+go run ./cmd/diunwebhook/
+```
+
+### Frontend (hot reload)
+
+The frontend dev server runs on `:5173` and proxies `/api` and `/webhook` requests to the Go backend on `:8080`:
+
+```bash
+cd frontend
+bun install
+bun run dev    # http://localhost:5173
+```
+
+Make sure the Go backend is running alongside the frontend dev server.
+
+### Docker Compose (dev)
+
+Builds the image locally from source:
+
+```bash
+docker compose -f compose.dev.yml up -d
+# open http://localhost:8080
+```
+
+## Building from Source
+
+```bash
+# 1. Build the frontend
+cd frontend && bun install && bun run build && cd ..
+
+# 2. Build the Go binary
+go build -o app ./cmd/diunwebhook/
+
+# 3. Run it (frontend/dist/ must be in the working directory)
+./app
+```
+
+## Testing
+
+Run all tests with coverage:
+
+```bash
+go test -v -coverprofile=coverage.out -coverpkg=./... ./...
+```
+
+Run a single test:
+
+```bash
+go test -v -run TestWebhookHandler ./pkg/diunwebhook/
+```
+
+Aim for 80-90% coverage. Coverage below 80% will emit a warning in CI but will not fail the pipeline.
+
+## CI/CD
+
+### CI Pipeline
+
+**Workflow:** `.gitea/workflows/ci.yml`
+**Trigger:** push or PR to `develop`
+
+Steps:
+1. Check formatting (`gofmt`)
+2. Run `go vet`
+3. Run tests with coverage
+4. Build the binary
+
+### Release Pipeline
+
+**Workflow:** `.gitea/workflows/release.yml`
+**Trigger:** manual dispatch
+
+Steps:
+1. Run tests
+2. Bump version and tag
+3. Build and push Docker image to Gitea registry
+4. Create a Gitea release with changelog
+
+## Documentation
+
+The documentation site is built with [VitePress](https://vitepress.dev/) and lives in `docs/`.
+
+```bash
+cd docs
+bun install        # install deps
+bun run dev        # dev server on :5174
+bun run build      # production build
+bun run preview    # preview the build
+```