feat(categories): detail page with fleet insights

Clicking a category anywhere in the app now opens /categories/:id with
MPN breakdown, manufacturer mix, failures by MPN, and past-EOL exposure
— a dual of the manufacturer detail page.

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

apps/web/src/lib/api/categories.ts

@@ -1,4 +1,8 @@
-import type { CreateCategoryRequest, UpdateCategoryRequest } from '@vector/shared';
+import type {
+  CategoryInsights,
+  CreateCategoryRequest,
+  UpdateCategoryRequest,
+} from '@vector/shared';
 import { api } from './client.js';
 import { getList } from './paginated.js';
 import type { Category } from './types.js';
@@ -7,6 +11,16 @@ export function listCategories(filters: { page?: number; pageSize?: number } = {
   return getList<Category>('/categories', filters);
 }
 
+export async function getCategory(id: string): Promise<Category> {
+  const res = await api.get<Category>(`/categories/${id}`);
+  return res.data;
+}
+
+export async function getCategoryInsights(id: string): Promise<CategoryInsights> {
+  const res = await api.get<CategoryInsights>(`/categories/${id}/insights`);
+  return res.data;
+}
+
 export async function createCategory(input: CreateCategoryRequest): Promise<Category> {
   const res = await api.post<Category>('/categories', input);
   return res.data;

apps/web/src/lib/api/types.ts

@@ -165,8 +165,10 @@ export interface Tag {
 export interface Category {
   id: string;
   name: string;
+  description?: string | null;
   createdAt: string;
   updatedAt: string;
+  _count?: { partModels: number };
 }
 
 export interface FmProblemPart {

apps/web/src/lib/queryKeys.ts

@@ -86,6 +86,8 @@ export const queryKeys = {
     all: ['categories'] as const,
     list: (filters?: Record<string, unknown>) =>
       [...queryKeys.categories.all, 'list', filters ?? {}] as const,
+    detail: (id: string) => [...queryKeys.categories.all, 'detail', id] as const,
+    insights: (id: string) => [...queryKeys.categories.all, 'insights', id] as const,
   },
   webhooks: {
     all: ['webhooks'] as const,