Add Gitea Actions CI/CD for automated Docker builds

- Add .gitea/workflows/docker.yml: builds and pushes Docker image on Git tags
  with semantic versioning (v0.1.0 → tags 0.1.0, 0.1, latest)
- Add .dockerignore to optimize Docker build context
- Document release process in docs/DEVELOPMENT.md
- Update CHANGELOG.md with v0.1.0 release and Unreleased CI/CD entry

Required Gitea secrets: REGISTRY_USERNAME, REGISTRY_PASSWORD

Co-authored-by: Junie <junie@jetbrains.com>

docs/DEVELOPMENT.md

@@ -91,6 +91,59 @@ docker run -d \
   htop-web
 ```
 
+## Release process
+
+### Prerequisites
+
+- Gitea Actions runner must be configured and running.
+- Repository secrets `REGISTRY_USERNAME` and `REGISTRY_PASSWORD` must be set in **Settings → Secrets** of the Gitea repository. These credentials are used to authenticate with the Gitea Container Registry.
+
+### Creating a release
+
+1. **Update `CHANGELOG.md`** with changes for the new version.
+
+2. **Commit and push** your changes:
+
+   ```bash
+   git add -A
+   git commit -m "Prepare release v0.2.0"
+   git push origin master
+   ```
+
+3. **Create and push a Git tag** with Semantic Versioning:
+
+   ```bash
+   git tag -a v0.2.0 -m "Release v0.2.0: new features and fixes"
+   git push origin v0.2.0
+   ```
+
+4. **Gitea Actions** will automatically:
+   - Build the Docker image using the multi-stage Dockerfile
+   - Tag it with the version (`0.2.0`), minor version (`0.2`), and `latest`
+   - Push all three tags to the Gitea Container Registry
+
+### Docker image tags
+
+Each release produces three Docker image tags:
+
+| Tag | Example | Description |
+|-----|---------|-------------|
+| Full version | `gitea.jambotron.com/liosha84/htop-web:0.2.0` | Exact version, use in production |
+| Minor version | `gitea.jambotron.com/liosha84/htop-web:0.2` | Latest patch of 0.2.x |
+| Latest | `gitea.jambotron.com/liosha84/htop-web:latest` | Most recent stable release |
+
+### Using a specific version in production
+
+In `docker-compose.yml`, always pin to a specific version:
+
+```yaml
+services:
+  htop-web:
+    image: gitea.jambotron.com/liosha84/htop-web:0.2.0
+```
+
+Avoid using `:latest` in production — it makes rollbacks impossible and breaks reproducibility.
+
 ## Contribution guidelines
 
 - Keep changes focused and reviewable.