control board: stale registrations and a launch-test leak (#1504)

Two defects in 69f99323, reported by the professor session and verified.

The darkwing launch test's flock-contention spawn ran without the fixture
config, so launch.sh re-entered scripts/mosaic against the real data root
and wrote fixture records for darkwing, dewey and filbert there. That
spawn now names the fixture config, and both launch test files set
MOSAIC_CONFIG to a nonexistent path and clear MOSAIC_LAUNCH_REGISTERED
process-wide, so a spawn that forgets fails instead of polluting.

A registration is written before the launch script's own checks, so a
refused launch left a record with a dead pid that the board honoured. The
scanner now probes the recorded pid (pidAlive, signal 0); a gone pid makes
the record stale: still on the Registered line with alive false, derived
task, project and workspace win, index gains registrationStale, CLI
summary gains a stale count.

Fleet launchers marked not planned per Jason. Board 90/90, seat 15/15,
launch scripts 5/5. Sonnet review APPROVED.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

scripts/test-rocko-launch.mjs

@@ -7,6 +7,10 @@ import { join, resolve } from 'node:path';
 import { spawnSync } from 'node:child_process';
 
 const source = resolve(import.meta.dirname, '..');
+// Every spawn below must name the fixture config explicitly. Anything that
+// forgets inherits these and fails instead of registering into a real data root.
+process.env.MOSAIC_CONFIG = join(tmpdir(), 'mosaic-launch-test-no-config.json');
+process.env.MOSAIC_LAUNCH_REGISTERED = '';
 test('Rocko uses Sonnet, isolated resume IDs, current context and launch refusals', () => {
   const root = mkdtempSync(join(tmpdir(), 'rocko launch '));
   try {