Add configurable database path via environment variables

- Add DATABASE_PATH environment variable support in app.py and aerich_config.py
- DATABASE_PATH: For simple relative/absolute paths (default: database/raggr.db)
- DATABASE_URL: For full connection strings (overrides DATABASE_PATH if set)
- Create .env.example with all configuration options documented
- Maintains backward compatibility with default database location

Usage:
  # Use default path
  python app.py

  # Use custom path for development
  DATABASE_PATH=dev.db python app.py

  # Use full connection string
  DATABASE_URL=sqlite://custom/path.db python app.py

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.env.example

@@ -0,0 +1,28 @@
+# Database Configuration
+# Use DATABASE_PATH for simple relative/absolute paths (e.g., "database/raggr.db" or "dev.db")
+# Or use DATABASE_URL for full connection strings (e.g., "sqlite://database/raggr.db")
+DATABASE_PATH=database/raggr.db
+# DATABASE_URL=sqlite://database/raggr.db
+
+# JWT Configuration
+JWT_SECRET_KEY=your-secret-key-here
+
+# Paperless Configuration
+PAPERLESS_TOKEN=your-paperless-token
+BASE_URL=192.168.1.5:8000
+
+# Ollama Configuration
+OLLAMA_URL=http://192.168.1.14:11434
+OLLAMA_HOST=http://192.168.1.14:11434
+
+# ChromaDB Configuration
+CHROMADB_PATH=/path/to/chromadb
+
+# OpenAI Configuration
+OPENAI_API_KEY=your-openai-api-key
+
+# Immich Configuration
+IMMICH_URL=http://192.168.1.5:2283
+IMMICH_API_KEY=your-immich-api-key
+SEARCH_QUERY=simba cat
+DOWNLOAD_DIR=./simba_photos