Add separate version tracking for artifacts

- Add package_versions table with immutable version records
- Support version detection from explicit param, metadata, or filename
- Add version API endpoints (list, get, delete)
- Update ref resolution to check versions before tags
- Add version column to tags table in frontend UI
- Add Create Tag form for pointing tags at existing artifacts
- Update seed data with version records
- Add 16 integration tests for version functionality

backend/app/metadata.py

@@ -245,9 +245,10 @@ def extract_tarball_metadata(file: BinaryIO, filename: str) -> Dict[str, Any]:
             break
 
     # Try to split name and version
+    # Handle optional 'v' prefix on version (e.g., package-v1.0.0)
     patterns = [
-        r"^(.+)-(\d+\.\d+(?:\.\d+)?(?:[-._]\w+)?)$",  # name-version
-        r"^(.+)_(\d+\.\d+(?:\.\d+)?(?:[-._]\w+)?)$",   # name_version
+        r"^(.+)-v?(\d+\.\d+(?:\.\d+)?(?:[-_]\w+)?)$",  # name-version or name-vversion
+        r"^(.+)_v?(\d+\.\d+(?:\.\d+)?(?:[-_]\w+)?)$",  # name_version or name_vversion
     ]
 
     for pattern in patterns: