feat(app): create new modular entry point

Add app.py as the new application entry point:
- Create main() function to initialize the application
- Import modules from the new package structure
- Handle multiprocessing with __mp_main__ check

🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

Author: jonathan-irvin

app.py

@@ -0,0 +1,32 @@
+# Main entry point for the application
+import logging
+from nicegui import ui, app
+from fastapi.staticfiles import StaticFiles
+
+# Import our modules
+from src.config.constants import HEADER_TEXT
+from src.ui.pages import setup_pages, home_page, stream_page
+from src.core.phrases import initialize_phrases
+from src.core.board import generate_board, board_iteration
+
+# Set up logging
+logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(message)s')
+
+def main():
+    # Initialize core components
+    initialize_phrases()
+    
+    # Generate initial board
+    generate_board(board_iteration)
+    
+    # Set up routes and pages
+    setup_pages()
+    
+    # Mount static files
+    app.mount("/static", StaticFiles(directory="static"), name="static")
+    
+    # Run the app
+    ui.run(port=8080, title=f"{HEADER_TEXT}", dark=False)
+
+if __name__ in {"__main__", "__mp_main__"}:
+    main()