fix: stamp CFBundleVersion into app bundle and repo during build & release

[Copilot]

setup/setup.py had hardcoded CFBundleVersion/CFBundleShortVersionString ('1.0.0') that were never touched by the workflow, so every built .app reported the wrong version to macOS (Finder "Get Info", Spotlight, system dialogs). The in-app About dialog was fine since it reads APP_VERSION from core.py, which was already stamped.

Changes

• Build job — "Stamp version into source": extends the Python stamping step to also patch CFBundleVersion and CFBundleShortVersionString in setup/setup.py before py2app runs, so the distributed .app bundle carries correct macOS metadata:

  p = pathlib.Path('setup/setup.py')
  text = p.read_text()
  text = re.sub(r"'CFBundleVersion': '[^']*'", f"'CFBundleVersion': '{ver}'", text)
  text = re.sub(r"'CFBundleShortVersionString': '[^']*'", f"'CFBundleShortVersionString': '{ver}'", text)
  p.write_text(text)

• Release job — "Finalize version bump and tag": adds sed commands for setup/setup.py and includes it in the version-bump commit pushed to main.

• Cleanup: removed the redundant src/syndi.py stamping — that file only imports APP_VERSION, never defines it, so those substitutions were no-ops.