feat: rework EOL, repairs, and hosts for real workflow

Four domain-model changes driven by exercising the deployed 2.0 build:

- EOL moves from manufacturer to MPN via new PartModel catalog table,
  so alerts fire on the thing that actually ages.
- Repairs re-home to Host (required hostId + problem text) with an
  optional RepairJobPart join for affected parts; drop Part.replacementPartId.
- New /repairs/:id detail page with editable problem, part list, and
  a RepairComment thread (REPAIR_COMMENTED events fan out to each
  problem part's timeline).
- Host.assetId (required, unique) surfaces prominently on the repair
  page so techs can confirm they're touching the right box.

Single destructive migration reshapes existing dev data. All 7 packages
typecheck clean; 30 API tests pass (9 new covering host membership,
upsertByMpn idempotency + race, assetId 409, comment userId stamping).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/api/src/routes/hosts.ts

@@ -13,6 +13,7 @@ const router = Router();
 router.get('/', requireAuth, validate('query', HostListQuery), ctrl.list);
 router.post('/', requireAuth, requireRole('ADMIN'), validate('body', CreateHostRequest), ctrl.create);
 router.get('/:id', requireAuth, ctrl.get);
+router.get('/:id/deployed-parts', requireAuth, ctrl.listDeployedParts);
 router.patch('/:id', requireAuth, requireRole('ADMIN'), validate('body', UpdateHostRequest), ctrl.update);
 router.delete('/:id', requireAuth, requireRole('ADMIN'), ctrl.remove);