Flatten repo structure: move crawler/ to root, remove vqa/ and immoweb/

The crawler subdirectory was the only active project. Moving it to the
repo root simplifies paths and removes the unnecessary nesting. The
vqa/ and immoweb/ directories were legacy/unused and have been removed.

Updated .drone.yml, .gitignore, .claude/ docs, and skills to reflect
the new flat structure.

notifications.py

@@ -0,0 +1,29 @@
+from abc import abstractmethod
+import apprise
+from functools import lru_cache
+import os
+
+
+class Surface:
+    @abstractmethod
+    def connection_string(self) -> str | None: ...
+
+
+class Slack(Surface):
+    def connection_string(self) -> str | None:
+        return os.environ.get("SLACK_WEBHOOK_URL")
+
+
+@lru_cache(maxsize=None)
+def get_notifier(surfaces: list[Surface] | None = None) -> apprise.Apprise:
+    surfaces = surfaces or list[Surface]([Slack()])
+    obj = apprise.Apprise()
+    for surface in surfaces:
+        if conn := surface.connection_string():
+            obj.add(conn)
+    return obj
+
+
+async def send_notification(body: str, title: str = "") -> bool:
+    notifier = get_notifier()
+    return await notifier.async_notify(body=body, title=title)