Hash routing — %23 regression test harness

How to use: set the base URL for the environment you want to test, then click Open on each row. The control rows (real #) should always reach the Angular app. The %23 rows fail with a 404 before the fix, and should redirect to the proper hashed URL after the fix is deployed. The HEAD button does a fetch and reports the response type without leaving this page — useful for spotting redirects vs 404s, though browser CORS will hide the actual Location header for cross-origin responses (use curl -I for that).