Refactor codebase following Clean Code principles and add 229 tests

- Extract helpers to reduce function sizes (listing_tasks, app.py, query.py, listing_fetcher)
  - Replace nonlocal mutations with _PipelineState dataclass in listing_tasks
  - Fix bugs: isinstance→equality check in repository, verify_exp for OIDC tokens
  - Consolidate duplicate filter methods in listing_repository
  - Move hardcoded config to env vars with backward-compatible defaults
  - Simplify CLI decorator to auto-build QueryParameters
  - Add deprecation docstring to data_access.py
  - Test count: 158 → 387 (all passing)

crawler/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