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.

tests/unit/test_route_calculator.py

@@ -0,0 +1,10 @@
+"""Unit tests for services/route_calculator.py."""
+from services.route_calculator import _parse_duration
+
+
+class TestParseDuration:
+    def test_parse_normal_duration(self) -> None:
+        assert _parse_duration("123s") == 123
+
+    def test_parse_zero_duration(self) -> None:
+        assert _parse_duration("0s") == 0