feat(profile): add help screen and fix upload field name

Add dedicated Help screen to profile tab with navigation integration.
Refactor SettingsScreen to navigate to HelpScreen instead of showing placeholder alert.
Fix API upload method to use correct field names ("file" for documents, "image" for media)
based on endpoint path, resolving upload failures for file uploads.

app/(app)/(tabs)/profile/_layout.tsx

@@ -17,6 +17,7 @@ export default function ProfileStackLayout() {
       <Stack.Screen name="blocked-users" />
       <Stack.Screen name="chat-settings" />
       <Stack.Screen name="about" />
+      <Stack.Screen name="help" />
       <Stack.Screen name="verification" />
       <Stack.Screen name="data-storage" />
       <Stack.Screen name="privacy-settings" />

app/(app)/(tabs)/profile/help.tsx

@@ -0,0 +1,5 @@
+import { HelpScreen } from '../../../../src/screens/profile';
+
+export default function HelpRoute() {
+  return <HelpScreen />;
+}