feat: Add dynamic Git-based versioning system

- Add app/version.py module generating version from Git metadata
- Format: YYYY.MM.DD+<commit_hash> (e.g., 2025.01.18+576c8ca9)
- Add +dirty suffix for uncommitted changes (ignores .env, technotes/)
- Add /api/version endpoint for monitoring
- Display version in hamburger menu
- Add freeze mechanism for Docker builds

Deploy command updated:
git push && ssh ... "cd ~/mc-webui && git pull && python -m app.version freeze && docker compose up -d --build"

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Dockerfile

@@ -16,6 +16,8 @@ COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
 # Copy application code
+# Note: Run 'python -m app.version freeze' before build to include version info
+# The version_frozen.py file will be copied automatically if it exists
 COPY app/ ./app/
 
 # Expose Flask port