feat(navi): GPS origin + place detail panel + basic actions

Adds synthetic "Your location" stop A when GPS granted; place
detail panel slides in on search result click with Directions /
Add stop / Save (stub) / Share actions; elevation via Valhalla
/height; react-hot-toast for feedback; pendingDestination state
for GPS-denied Directions flow.

Phase 3 Step 5 C1 of Navi.

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

src/main.jsx

@@ -1,10 +1,23 @@
 import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
+import { Toaster } from 'react-hot-toast'
 import './index.css'
 import App from './App.jsx'
 
 createRoot(document.getElementById('root')).render(
   <StrictMode>
     <App />
+    <Toaster
+      position="bottom-center"
+      toastOptions={{
+        style: {
+          background: 'var(--bg-overlay)',
+          color: 'var(--text-primary)',
+          border: '1px solid var(--border)',
+          fontSize: 'var(--text-sm)',
+          fontFamily: 'var(--font-sans)',
+        },
+      }}
+    />
   </StrictMode>,
 )