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.

crawler/frontend/Caddyfile.dev

@@ -1,11 +0,0 @@
-{$DEV_HOST:localhost}:443 {
-    tls internal
-
-    handle /api/* {
-        reverse_proxy app:5001
-    }
-
-    handle {
-        reverse_proxy frontend:5173
-    }
-}