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>

packages/db/prisma/schema.prisma

@@ -62,6 +62,8 @@ model PartModel {
   eolDate        DateTime?
   destroyOnFail  Boolean      @default(false)
   notes          String?
+  categoryId     String?
+  category       Category?    @relation(fields: [categoryId], references: [id], onDelete: SetNull)
   createdAt      DateTime     @default(now())
   updatedAt      DateTime     @updatedAt
   parts          Part[]
@@ -69,6 +71,7 @@ model PartModel {
   @@unique([manufacturerId, mpn])
   @@index([manufacturerId])
   @@index([eolDate])
+  @@index([categoryId])
 }
 
 model Site {
@@ -106,12 +109,12 @@ model Bin {
 }
 
 model Category {
-  id          String   @id @default(uuid())
-  name        String   @unique
+  id          String      @id @default(uuid())
+  name        String      @unique
   description String?
-  createdAt   DateTime @default(now())
-  updatedAt   DateTime @updatedAt
-  parts       Part[]
+  createdAt   DateTime    @default(now())
+  updatedAt   DateTime    @updatedAt
+  partModels  PartModel[]
 }
 
 model Part {
@@ -125,8 +128,6 @@ model Part {
   state              String       @default("SPARE")
   binId              String?
   bin                Bin?         @relation(fields: [binId], references: [id], onDelete: SetNull)
-  categoryId         String?
-  category           Category?    @relation(fields: [categoryId], references: [id], onDelete: SetNull)
   hostId             String?
   host               Host?        @relation(fields: [hostId], references: [id], onDelete: SetNull)
   custodianId        String?
@@ -144,7 +145,6 @@ model Part {
   @@index([binId])
   @@index([manufacturerId])
   @@index([partModelId])
-  @@index([categoryId])
   @@index([hostId])
   @@index([custodianId])
 }
@@ -191,11 +191,16 @@ model Host {
   name      String   @unique
   location  String?
   notes     String?
+  state     String   @default("DEPLOYED")
+  stack     String   @default("PRODUCTION")
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
   parts     Part[]
   fms       Fm[]
   repairs   Repair[]
+
+  @@index([state])
+  @@index([stack])
 }
 
 model Fm {