feat(manufacturers): detail page with MPN-level insights

Adds /manufacturers/:id with vendor-wide KPIs, top MPNs by units,
failures by MPN, category mix, past-EOL exposure, and a filtered
PartModels table. Wires upstream links from PartDetail and
PartModelDetail so the manufacturer name is a navigable anchor.

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

packages/shared/src/index.ts

@@ -19,3 +19,4 @@ export * from './saved-views.js';
 export * from './csv-imports.js';
 export * from './analytics.js';
 export * from './part-model-insights.js';
+export * from './manufacturer-insights.js';

packages/shared/src/manufacturer-insights.ts

@@ -0,0 +1,49 @@
+export interface ManufacturerPriceStats {
+  total: number;
+  average: number;
+  min: number | null;
+  max: number | null;
+  countWithPrice: number;
+}
+
+export interface ManufacturerFailureStats {
+  repairs: number;
+  distinctFailedParts: number;
+  fmsImplicating: number;
+}
+
+export interface ManufacturerCategoryCount {
+  categoryId: string | null;
+  categoryName: string;
+  count: number;
+}
+
+export interface ManufacturerModelCount {
+  partModelId: string;
+  mpn: string;
+  count: number;
+}
+
+export interface ManufacturerModelFailureCount {
+  partModelId: string;
+  mpn: string;
+  repairs: number;
+}
+
+export interface ManufacturerPastEolModel {
+  partModelId: string;
+  mpn: string;
+  eolDate: string;
+  deployedCount: number;
+}
+
+export interface ManufacturerInsights {
+  totalPartModels: number;
+  totalParts: number;
+  priceStats: ManufacturerPriceStats;
+  failures: ManufacturerFailureStats;
+  byCategory: ManufacturerCategoryCount[];
+  topModelsByUnits: ManufacturerModelCount[];
+  failuresByModel: ManufacturerModelFailureCount[];
+  pastEolModels: ManufacturerPastEolModel[];
+}