chore: CI/build improvements and version detection

- Rename GITEA_TOKEN to DEPLOY_TOKEN in release workflow
- Extract shared version detection into build-common.sh
- Use importlib.metadata for runtime version instead of hardcoded string
- Use PEP 440 parsing (packaging lib) for update version comparison
- Add packaging>=23.0 to dependencies
- Fix update banner close button alignment (CSS)
- Update CLAUDE.md with versioning docs and frontend rebuild notes

media_server/services/update_checker.py

@@ -2,30 +2,36 @@
 
 import asyncio
 import logging
+import re
 from typing import Any, Optional
 
+from packaging.version import Version
+
 from .release_provider import ReleaseProvider
 from .websocket_manager import ws_manager
 
 logger = logging.getLogger(__name__)
 
+_PRE_PATTERN = re.compile(
+    r"^(\d+\.\d+\.\d+)[-.]?(alpha|beta|rc)[.-]?(\d+)$", re.IGNORECASE
+)
+_PRE_MAP = {"alpha": "a", "beta": "b", "rc": "rc"}
 
-def _parse_version(version: str) -> tuple[int, ...]:
-    """Parse a version string into a comparable tuple.
 
-    Handles versions like "1.0.0", "1.2.3", ignoring non-numeric suffixes.
+def _parse_version(raw: str) -> Version:
+    """Normalize a version tag to PEP 440 for correct comparison.
+
+    Examples:
+        v0.3.0-alpha.1 → 0.3.0a1  (pre-release, sorts below 0.3.0)
+        v0.3.0-rc.3    → 0.3.0rc3
+        v1.0.0         → 1.0.0
     """
-    parts: list[int] = []
-    for part in version.split("."):
-        digits = ""
-        for ch in part:
-            if ch.isdigit():
-                digits += ch
-            else:
-                break
-        if digits:
-            parts.append(int(digits))
-    return tuple(parts)
+    cleaned = raw.lstrip("v").strip()
+    m = _PRE_PATTERN.match(cleaned)
+    if m:
+        base, pre_label, pre_num = m.group(1), m.group(2).lower(), m.group(3)
+        cleaned = f"{base}{_PRE_MAP[pre_label]}{pre_num}"
+    return Version(cleaned)
 
 
 class UpdateChecker: