Add main application structure and logging configuration

- Implement main application entry point in duck-ocr.py
- Create logging configuration in logging_config.py
- Add video streaming functionality in camera.py
- Introduce main window UI in main_window.py
- Include SVG assets for UI buttons and icons
- Update .gitignore to exclude log files
- Add placeholder .gitkeep files for empty directories

app/logging_config.py

@@ -0,0 +1,46 @@
+# logging_config.py
+
+import logging
+import logging.handlers
+from pathlib import Path
+
+
+LOG_DIR = Path("logs")
+LOG_DIR.mkdir(exist_ok=True)
+
+LOG_FILE = LOG_DIR / "app.log"
+
+
+def setup_logging():
+    formatter = logging.Formatter(
+        fmt="%(asctime)s | %(levelname)-8s | %(threadName)s | %(name)s | %(message)s",
+        datefmt="%Y-%m-%d %H:%M:%S",
+    )
+
+    # logger główny
+    logger = logging.getLogger()
+
+    logger.setLevel(logging.DEBUG)
+
+    # zabezpieczenie przed dodaniem handlerów drugi raz
+    if logger.handlers:
+        return
+
+    # console
+    console_handler = logging.StreamHandler()
+    console_handler.setLevel(logging.INFO)
+    console_handler.setFormatter(formatter)
+
+    # plik
+    file_handler = logging.handlers.RotatingFileHandler(
+        LOG_FILE,
+        maxBytes=5_000_000,
+        backupCount=3,
+        encoding="utf-8",
+    )
+
+    file_handler.setLevel(logging.DEBUG)
+    file_handler.setFormatter(formatter)
+
+    logger.addHandler(console_handler)
+    logger.addHandler(file_handler)