Test that a URL made on the generator page with a ttl expires (closes #199)

A new handler test makes a URL on the generator page with a ttl of one
second, checks that /v1/e/ serves it at once, waits two seconds and
checks that it then answers 410. The expiry is kept in whole seconds,
so two seconds is the longest a one-second ttl can take to pass. Test
only.

Model: opus-5-5

TODO.md

@@ -31,6 +31,13 @@ P2: security: per-IP rate limiting on the image routes
 
 # Completed Steps
 
+- 2026-10-04 a URL made on the generator page with a `ttl` is tested to
+  expire (closes #199): a new test in `internal/handlers` makes a URL on the
+  generator page with a `ttl` of one second, checks that `/v1/e/` serves it at
+  once, waits two seconds and checks that it then answers 410. The test waits
+  for real, as pixa reads the clock directly when it makes and checks a URL; it
+  waits two seconds because the time a URL expires is kept in whole seconds.
+  Test only.
 - 2026-10-04 referer blocklist (closes #90): `referer_blocklist`
   (`PIXA_REFERER_BLOCKLIST`) lists hosts, written and matched as for
   `allowlist_hosts` with the same matcher; an entry of either list that is