Fix map recenter (root cause), login logo/theming, policy pricing display

- ROOT CAUSE: MapLibre Camera re-applies its last setCamera() stop on every
  re-render, so a search (setZones) snapped the map back to the last programmatic
  target. Memoize the Camera + UserLocation elements so search re-renders never
  touch them; only the marker ShapeSource updates. (Confirmed via [CAM] trace.)
- Login: brain-car logo + full theming so text is readable in light/dark
- Meter policies: negative Rate is a sentinel (RateType No Parking=-1 / Free=-3),
  not a price; show DisplayString + colored type dot, real $/hr only when positive.
  Fix zone rate "$ 4.00" formatting.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/src/screens/MapScreen.tsx

@@ -178,6 +178,29 @@ export function MapScreen() {
     }
   };
 
+  // MapLibre's Camera re-applies its last imperative setCamera() stop whenever it
+  // re-renders — so a search re-render (setZones) would snap the map back to the
+  // last programmatic target. Memoize these elements so search re-renders never
+  // touch them; only the marker ShapeSource below updates.
+  const cameraEl = useMemo(() => <Camera ref={cameraRef} />, []);
+  const userLocationEl = useMemo(
+    () => (
+      <UserLocation
+        visible
+        renderMode="normal"
+        onUpdate={(loc: any) => {
+          if (loc?.coords) {
+            nativeFix.current = {
+              latitude: loc.coords.latitude,
+              longitude: loc.coords.longitude,
+            };
+          }
+        }}
+      />
+    ),
+    [],
+  );
+
   return (
     <View style={styles.container}>
       <MapView
@@ -198,25 +221,8 @@ export function MapScreen() {
           )
         }
       >
-        {/* Uncontrolled camera; we position it imperatively (once on load, then
-            only on explicit user actions) so re-renders never move the map. */}
-        <Camera ref={cameraRef} />
-
-        {/* renderMode="normal" draws the dot in the JS layer and does NOT engage
-            the native location component, which was tracking the camera back to
-            the user on re-render. */}
-        <UserLocation
-          visible
-          renderMode="normal"
-          onUpdate={(loc: any) => {
-            if (loc?.coords) {
-              nativeFix.current = {
-                latitude: loc.coords.latitude,
-                longitude: loc.coords.longitude,
-              };
-            }
-          }}
-        />
+        {cameraEl}
+        {userLocationEl}
 
         <ShapeSource id="meters" shape={meterFeatures} onPress={onPinPress}>
           <CircleLayer