feat(F020): frontend infrastructure foundation

- src/lib/constants.ts: centralized route paths, labels, thresholds
- src/lib/utils.ts: formatting, color helpers, math utils
- src/hooks/: useProperties, useMatches, useFutureSignals, useNeeds
- src/components/scores/MatchScoreRing
- src/components/data-quality/DataQualityBar
- src/components/future-signals/SignalTypeBadge
- src/components/cards/SourceTypeBadge
- src/provider/AuthProvider (placeholder, swappable)
- main.tsx: AuthProvider + centralized stale time

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/hooks/useNeeds.ts

@@ -0,0 +1,19 @@
+import { useQuery } from '@tanstack/react-query'
+import { needService } from '../services/needService'
+
+export function useNeeds() {
+  return useQuery({
+    queryKey: ['needs'],
+    queryFn: () => needService.getAll(),
+    select: (res) => res.data ?? [],
+  })
+}
+
+export function useNeed(id: string) {
+  return useQuery({
+    queryKey: ['need', id],
+    queryFn: () => needService.getById(id),
+    enabled: Boolean(id),
+    select: (res) => res.data ?? null,
+  })
+}