Update OPENCODE.md with Dockerfile docs and CI/CD information

Changes:
- Add Dockerfile Configuration section with code example
- Document Debian-based image choice (python:3.11-slim)
- Add all system dependencies (libgl1, libsm6, etc.)
- Extend Common Issues with Docker build troubleshooting
- New CI/CD section for Gitea Actions
- Document both workflows (autobuild and manual)
- Add required secrets and registry configuration
- Add version history overview

OPENCODE.md

@@ -13,25 +13,31 @@ This is a Telegram bot for managing sticker packs. Built with python-telegram-bo
 - **Video Processing**: FFmpeg for GIF to WebM conversion
 - **Background Removal**: rembg (local) + remove.bg API (optional)
 - **Container**: Docker + Docker Compose
+- **Base Image**: python:3.11-slim (Debian-based for better compatibility)
 - **Environment**: python-dotenv for configuration
 
-### Project Structure
-```
-stickerbot/
-├── bot.py                   # Main bot with ConversationHandler
-├── config.py                # Configuration and environment loading
-├── database.py              # SQLite database operations
-├── sticker_manager.py       # Sticker management utilities
-├── image_processor.py       # Automatic image conversion
-├── gif_processor.py         # GIF to WebM conversion
-├── background_remover.py    # Background removal (local + API)
-├── requirements.txt         # Python dependencies
-├── Dockerfile              # Docker image configuration
-├── docker-compose.yml      # Docker Compose configuration
-├── .env.example            # Environment template
-└── data/                   # Persistent data directory
+### Dockerfile Configuration
+```dockerfile
+FROM python:3.11-slim
+
+# System dependencies for OpenCV, FFmpeg and rembg
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    ffmpeg \
+    libgl1 \
+    libglib2.0-0 \
+    libsm6 \
+    libxext6 \
+    libxrender-dev \
+    libgomp1 \
+    && rm -rf /var/lib/apt/lists/*
 ```
 
+**Key points:**
+- Uses `python:3.11-slim` (Debian-based) instead of Alpine for better Python package compatibility
+- Includes OpenCV dependencies: `libgl1`, `libglib2.0-0`, `libsm6`, `libxext6`, `libxrender-dev`
+- Includes `libgomp1` for OpenMP support (required by numba/llvmlite)
+- Non-root user for security
+
 ### Database Schema
 - **sticker_sets**: Tracks created sticker sets (user_id, set_name, set_title, timestamps)
 - **user_premium**: Caches user premium status with last check timestamp
@@ -321,9 +327,21 @@ sudo docker-compose up -d --build --force-recreate
 5. **API limit reached**: Check current usage with `/hilfe` or in database
 6. **Background removal slow**: First run downloads ML model (~180MB)
 7. **GIF conversion fails**: Ensure GIF is under 10MB before upload
+8. **Docker build fails with Alpine**: We use `python:3.11-slim` (Debian) instead of Alpine because rembg requires compilation tools that don't work well with Alpine's musl libc
 
 ## Troubleshooting
 
+### Docker Build Issues
+If the Docker build fails with package errors:
+```bash
+# The Dockerfile uses Debian-based python:3.11-slim
+# NOT Alpine - this is intentional for better Python package compatibility
+
+# Check Dockerfile has correct base image:
+grep "FROM" Dockerfile
+# Should show: FROM python:3.11-slim
+```
+
 ### Bot not responding
 ```bash
 # Check if container is running
@@ -344,3 +362,59 @@ sudo docker-compose restart
 - Verify REMOVE_BG_API_KEY is correct
 - Check API usage in database: `sqlite3 data/sticker_bot.db "SELECT * FROM api_usage;"`
 - API automatically falls back to local processing on errors
+
+## CI/CD with Gitea Actions
+
+The project includes automated Docker builds via Gitea Actions.
+
+### Workflow Files
+
+**`.gitea/workflows/docker-autobuild.yaml`** - Automatic builds on push
+- Triggers on push to `main` or `master` branch
+- Builds and pushes to local registry: `192.168.88.201:5000`
+- Tags: `latest` and `v{run_number}-autobuild`
+- Features:
+  - Path ignores for markdown/docs changes
+  - Docker Buildx with layer caching
+  - Automatic cleanup after build
+
+**`.gitea/workflows/docker-build.yaml`** - Manual builds
+- Triggered manually via Gitea web interface
+- Options:
+  - Custom version tag (e.g., `1.0.0`, `v1.0.0`)
+  - Additional tags (comma-separated, e.g., `stable,production`)
+  - Toggle `latest` tag
+- Features:
+  - Flexible versioning
+  - Multiple tag support
+  - Docker layer caching
+
+### Required Secrets
+
+Configure these in Gitea repository settings:
+- `REGISTRY_USERNAME` - Username for Docker registry
+- `REGISTRY_PASSWORD` - Password for Docker registry
+
+### Registry Configuration
+
+Default registry: `192.168.88.201:5000`
+
+To change the registry, edit both workflow files:
+```yaml
+REGISTRY="your-registry:port"
+```
+
+## Version History
+
+See git log for detailed commit history:
+```bash
+git log --oneline
+```
+
+Current features:
+- ✅ Telegram Sticker Bot with full management capabilities
+- ✅ Automatic image optimization (WebP conversion)
+- ✅ GIF to Video Sticker conversion
+- ✅ Background removal (local + API)
+- ✅ Existing sticker set import
+- ✅ Gitea Actions CI/CD