Make the tests pass on a busy host (closes #240)

Tests that waited a few seconds for something to happen now wait 15 seconds.
The wait ends as soon as the condition holds, so a passing run takes no longer.

TestStreamNotDroppedWhileLinesArrive runs on a fake clock, so a stall on the
host cannot use up its idle timeout.

The checkpoint tests give the writing connection a 30-second busy timeout, so
their limit can be 15 seconds and a checkpoint that waits for a read still
fails them.

Model: opus-5-5

TODO.md

@@ -56,6 +56,9 @@ problem the run finds.
 
 # Completed Steps
 
+- 2026-11-10: the tests no longer fail when a busy host stalls for several
+  seconds. A wait for something that should happen is now 15 seconds. The test
+  that lines keep a stream up runs on a fake clock (closes #240)
 - 2026-11-05: the prefix page lists the prefix's origin changes, newest first.
   The routing table records each change, and the prefix handler writes them to a
   new `origin_changes` table. The database maintainer prunes each prefix to its