test/apps-busy.test.ts runs in under 10 s, every test under 1 s, proving what it proves today #10213

For: #1242 (every test fast; the gate runs every test). Replaces #1252, parked when #1163 was dropped. Measured 2026-11-09 with bun test test/apps-busy.test.ts on a crew machine: 19.8 s for the file.

Done looks like:

• [x] Each slow test keeps the invariant it proves, written as one line at its top; a test that proves nothing another does is deleted, naming the line in the commit.
• [x] Shared setup is built once per file (one forge, fixtures made once, a fake clock instead of real waits); no sleep longer than 50 ms remains.
• [x] bun test test/apps-busy.test.ts reports under 10 s on the crew machine, quoted in the pull with before and after; no test over 1 s.
• [x] The same number of invariants pass; nothing is skipped to get there.

Files: test/apps-busy.test.ts and its helpers under test/ only. Risk: a rewritten test that no longer fails without the code it guards; show one such failure per rewritten test in the pull.

Reviewed pull #10224 at its head: ticked Each slow test keeps the invariant it proves, written as one line at its top; a test that proves nothing another does is deleted, naming the line in the commit.; Shared setup is built once per file (one forge, fixtures made once, a fake clock instead of real waits); no sleep longer than 50 ms remains.; bun test test/apps-busy.test.ts reports under 10 s on the crew machine, quoted in the pull with before and after; no test over 1 s.; The same number of invariants pass; nothing is skipped to get there..