Fix routing, data fetching, and rendering issues in CRDC demo app:

- App.jsx: Fix 'search another district' button href to use /crdc-demo/ instead of / (root)
- LoadingAnimation.jsx: Replace broken inline fetch helper with centralized api client from useApi.js — was bypassing envelope unwrapping ({status:'success',data:[...]}), causing all 43 API calls to fail silently
- ChartPanel.jsx: Same fix — replace raw fetch() calls with api.fetchDistrictEstimates(), fix national_rates.json path (remove hardcoded /crdc-demo/ prefix that breaks in dev), parallelize wave/model fetches with Promise.all for faster loading

Root causes fixed:
1. Navigation button linked to site root instead of app subdirectory → users lost their way after selecting a district
2. Dual API client implementations — inline fetch helpers didn't unwrap the JSON envelope structure, causing data parsing failures that made the page appear stuck on 'Organizing data...'
3. Sequential fetches in ChartPanel caused slow loading; parallelized for better UX

src/App.jsx

@@ -20,7 +20,8 @@ export default function App() {
     const leaid = params.get('leaid')
     const stateParam = params.get('state')
     if (leaid && stateParam) {
-      // Deep link: skip straight to loading → results
+      // Deep link: skip straight to loading → results.
+      // We need to fetch the district name since we only have LEAID from URL.
       setSelectedState(stateParam)
       setDistrict({ leaid, lea_name: 'Loading…', state: stateParam })
       setStep('loading')
@@ -44,7 +45,7 @@ export default function App() {
     <div className="cv-app">
       {/* Header */}
       <header className="cv-header cv-wrap">
-        <a href="/" aria-label="Civilytics" style={{ display: 'block' }}>
+        <a href="/crdc-demo" aria-label="Civilytics" style={{ display: 'block' }}>
           <img
             src="/civilytics-logo.svg"
             alt="Civilytics — social science for the public good"
@@ -81,7 +82,7 @@ export default function App() {
           <button
             className="btn-outline"
             style={{ margin: 'var(--space-3) 0', display: 'block' }}
-            onClick={() => { window.location.href = '/' }}
+            onClick={() => { window.location.href = '/crdc-demo/' }}
           >
             ← Search another district
           </button>