Add collector PC->printer links and searchable custom fields

Collector: the computers collector schema gains defaultprinter and
printers; apply_collector_payload resolves each reported identifier to
a printer asset (windowsname/hostname/sharename/assetnumber/IP,
first-hit case-insensitive) and idempotently syncs relationships -
defaultprinter (directional) for the default, connectedto for the
rest. Collector-created rows are tagged so a re-report archives dropped
links while manual relationships are never touched; unresolved
identifiers warn instead of failing. Both PC and printer detail pages
show the links via the shared relationships card (no frontend change).
GE-Enforce Win32_Printer collection snippet documented.

Searchable custom fields: a per-field searchable flag (migration 7d24);
global search matches custom-field values on flagged active fields and
routes each hit to the asset detail page, reusing the existing
(type,id) dedupe and search_<type>_enabled domain filter. Searchable
toggle on the Custom Fields settings page.

822 tests pass; both verified live.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -22,6 +22,24 @@ ADR-007 and ADR-002.
 
 ### Added
 
+- Collector-driven PC -> printer relationships. The computers collector schema
+  gained optional `defaultprinter` (string) and `printers` (array of strings)
+  fields carrying Win32_Printer identifiers. On ingest each identifier resolves
+  to a printer asset (by windows name / share / hostname / asset number-name or
+  a communications IP) and the PC is linked to it: the default via a
+  `defaultprinter` relationship, the rest via `connectedto`. The links render in
+  the shared Relationships card on both the PC and printer detail pages. The
+  sync is idempotent and archives collector-created links to printers no longer
+  reported (tagged `assetrelationships.label = 'collector:printers'`, so
+  manually-created links are never touched); unresolved identifiers become
+  response warnings, never failures. The collector response carries
+  `printerlinkcount` and a `printerlinks` list. See docs/COLLECTOR-INTEGRATION.md.
+- Searchable custom fields. Each custom-field definition gained a `searchable`
+  flag (Settings > Custom Fields). When on, that field's stored values are
+  matched by global search and a hit routes to the owning asset's detail page.
+  The asset's `search_<type>_enabled` domain toggle still applies, and matches
+  dedupe against built-in-field asset hits so an asset appears once. Inactive or
+  non-searchable fields are never matched.
 - Single-label sheet-position printing. The single asset-label page
   (`/print/asset-label/:assettype/:id`) gained an Output control that toggles
   between the standalone label (unchanged default) and placing that one label at