feat: laundry-list polish pass

Seven bundled improvements:
- PartModel combobox on Add Part + Log Repair (known MPN auto-fills;
  unknown reveals manufacturer picker for catalog upsert).
- Host lifecycle: state (DEPLOYED/DEGRADED/TESTING) and stack
  (PRODUCTION/VETTING) fields, driven by external clients via the API.
- Locations page redesigned as a 2-pane tree + bin grid with breadcrumb.
- PENDING_REPAIR custody state: tech takes a SPARE into custody for a
  future swap; resolves to DEPLOYED via Repair or back to SPARE via a
  bin-required drop-off.
- Move Category from Part to PartModel; seed common categories
  (GPU/RAM/SSD/HDD/NIC/CPU/PSU/MOBO). Parts table gets a Category
  column and filter sourced from the model.
- Fix Deployed Value 100x bug on the Dashboard (price is stored as
  dollars, not cents).
- PartModels table shows "No" instead of "--" when destroyOnFail=false.

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

README.md

@@ -1,6 +1,6 @@
 # Vector
 
-Hardware parts inventory system. Tracks serialized parts across sites → rooms → bins, with a full audit trail, repair/RMA workflow, tag-based organization, manufacturer EOL tracking, and signed webhook delivery for external integrations.
+Hardware parts inventory system. Tracks serialized parts across sites → rooms → bins and hosts (with externally-driven state/stack lifecycle), with a full audit trail, repair/RMA workflow, per-tech custody for broken-part holds and pre-staged spares, tag-based organization, category-per-model taxonomy, manufacturer EOL tracking, and signed webhook delivery for external integrations.
 
 Vector 2.0 is a ground-up TypeScript rewrite of the original JavaScript codebase, delivered as a pnpm + Turbo monorepo with shadcn/ui on the frontend and a service-layered Express API on the backend.