refactor(webui): extract repeated dashboard elements into shared components

Markup and helpers that were copied between pages now live in one
place:
- ChartCard, StatDisabledAlert, StatItem, DetailField, BudgetRatioBars,
  LabeledSelect, TargetPicker and LoadStateView components
- lib/scope.ts, lib/columns.ts and lib/chart-palette.ts
- messageOf, isAuthRejection, and the USD to micro-USD conversion
  helpers
- one monthly cost projection, one date formatter, and the
  useCopyFeedback composable

Behaviour is unchanged. Before and after screenshots of every page
match at 390 and 1440 px. Empty-state text now comes from the shared
EmptyState component, and the user run-out date uses the short date
format. admin_assets_gen.go is regenerated.

Claude-Session: https://claude.ai/code/session_01V5jYJNxpDFdJkyyExpADrv

webui/src/stores/catalog.ts

@@ -1,6 +1,6 @@
 import { defineStore } from 'pinia'
 
-import { AdminApiError, adminFetch } from '@/lib/api'
+import { adminFetch, isAuthRejection, messageOf } from '@/lib/api'
 import { useAuthStore } from '@/stores/auth'
 import type { AdminCatalogModel, AdminCatalogResponse } from '@/types/api'
 
@@ -86,10 +86,10 @@ export const useCatalogStore = defineStore('catalog', {
         this.error = ''
       } catch (err) {
         if (requestId !== this.reqId) return
-        if (err instanceof AdminApiError && (err.status === 401 || err.status === 403)) {
+        if (isAuthRejection(err)) {
           return
         }
-        this.error = err instanceof Error ? err.message : String(err)
+        this.error = messageOf(err)
       } finally {
         if (requestId === this.reqId) this.loading = false
       }