Extracts notification logic into a reusable utility

Moves desktop notification functionality to a separate module for better code reuse and maintainability. Updates the main application to use the new utility.

notify.py

@@ -0,0 +1,22 @@
+import subprocess
+
+def notify(title: str, message: str) -> None:
+    """
+    Sends a desktop notification using the `notify-send` command.
+
+    Args:
+        title (str): The title of the notification.
+        message (str): The message content of the notification.
+
+    Raises:
+        subprocess.CalledProcessError: If the `notify-send` command fails.
+
+    Note:
+        This function requires the `notify-send` command to be available on the system.
+        It is typically available on Linux systems with a notification daemon running.
+    """
+    try:
+        subprocess.run(["notify-send", "-a", "Voice to Text", "-i", "audio-input-microphone", title, message], check=True)
+    except subprocess.CalledProcessError as e:
+        print("Fehler beim Benachrichtigen mit 'notify-send'.")
+        print(e)