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/components/GpsOriginItem.jsx

@@ -0,0 +1,33 @@
+/** Non-draggable "Your location" row at top of StopList when GPS is granted. */
+export default function GpsOriginItem() {
+  return (
+    <div
+      className="flex items-center gap-2 py-1.5 px-2 rounded"
+      style={{
+        background: 'var(--bg-overlay)',
+        border: '1px solid var(--border-subtle)',
+      }}
+    >
+      {/* Spacer matching drag handle width */}
+      <span className="w-[14px]" />
+
+      {/* ATAK chevron icon */}
+      <span className="w-5 h-5 flex items-center justify-center shrink-0">
+        <svg width="14" height="14" viewBox="0 0 16 16" xmlns="http://www.w3.org/2000/svg">
+          <path
+            d="M8 1 L14 13 L8 10 L2 13 Z"
+            fill="var(--accent)"
+            stroke="var(--pin-stroke)"
+            strokeWidth="1.5"
+            strokeLinejoin="round"
+          />
+        </svg>
+      </span>
+
+      {/* Label */}
+      <span className="flex-1 text-sm" style={{ color: 'var(--text-secondary)' }}>
+        Your location
+      </span>
+    </div>
+  )
+}