fix: one id per card, and render the site locally

A copy filed under two consoles of one maker was listed twice with the same id, and a data directory listed the same bytes twice, so the site deploy refused 20 pages. The first card keeps the id. The pipeline only generated the pages, so it now renders them with mkdocs build --strict and runs validate_site as the deploy does. The resumed-speed test read the clock and failed on a slow runner, it now fixes the elapsed time.

tests/test_install.py

@@ -2794,7 +2794,9 @@ class AResumedCopyIsNotSpeed(unittest.TestCase):
         term = install.Terminal(out)
         term.live = True
         progress = install.Progress(1, 4_000_000_000, term)
-        progress.start -= 10
+        # Ten seconds exactly: read from the clock, a slow runner added a few
+        # milliseconds and moved the last digit of the speed.
+        progress.elapsed = lambda: 10.0
         progress.bytes = 3_000_000_000 + 10_000_000
         progress.resumed = 3_000_000_000
         with unittest.mock.patch.object(