feat: host detail page + FM host context

Add /hosts/:id detail page with unified timeline (HostEvents + FMs + Repairs
+ part arrivals/departures) and a deployed-parts table. Hosts list rows now
link to the page. FM list + detail surface inline State/Stack badges next
to the asset ID, with the asset ID linking to the host page.

HostEvent audit model added; create/update in the hosts service now diff
and log state, stack, and field changes the same way parts.ts does.

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

apps/api/src/routes/hosts.ts

@@ -2,6 +2,7 @@ import { Router } from 'express';
 import {
   CreateHostRequest,
   HostListQuery,
+  HostTimelineQuery,
   UpdateHostRequest,
 } from '@vector/shared';
 import * as ctrl from '../controllers/hosts.js';
@@ -14,6 +15,7 @@ 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.get('/:id/timeline', requireAuth, validate('query', HostTimelineQuery), ctrl.getTimeline);
 router.patch('/:id', requireAuth, requireRole('ADMIN'), validate('body', UpdateHostRequest), ctrl.update);
 router.delete('/:id', requireAuth, requireRole('ADMIN'), ctrl.remove);