Improve Docker image tagging strategy and remove Swagger version

- Replace 'stable' tag with semver-based tags (1.2.3, 1.2, 1)
- Use 'edge' tag for main branch instead of 'latest'
- Reserve 'latest' tag only for tagged releases
- Remove version from Swagger docs (tracked via git tags instead)
- Document available image tags in README

README.md

@@ -50,6 +50,12 @@ docker-compose up -d
 
 The API will be available at `http://localhost:8080`
 
+**Available image tags:**
+- `latest`: Latest stable release (recommended for production)
+- `1`, `1.0`, `1.0.0`: Specific version tags
+- `edge`: Latest development build from main branch (unstable)
+- `sha-abc123`: Specific commit (for debugging)
+
 **Configuration options:**
 - `JWT_SECRET`: **Required**. Use a long random string
 - `JWT_EXPIRY`: Token expiration (e.g., `24h`, `48h`)