Add chat-first onboarding and intelligent context-based paywall

Replaces the hardcoded message limit with a model-driven paywall and
removes registration before the first question:

- Onboarding: the app opens directly into the chat. Dynamic conversation
  starters are served by GET /suggestions (services/api/suggestions.json),
  updatable with a deploy — no app release needed. Guests chat via
  POST /guest/chat, identified by an app-generated device id; sign-in
  moves to the paywall, where a purchase must attach to an account.
- Free experience: the model runs in discovery mode — follow-up
  questions, pattern identification, visible understanding — building an
  analysis without delivering the full solution.
- Intelligent paywall: the model returns structured output (reply +
  analysis_ready). Only when the problem is described, the information is
  sufficient and an action plan is ready does it write a calm transition
  and pause the conversation. Manufactured urgency, emotional pressure,
  fake readiness and mid-answer stops are explicitly forbidden.
- Premium: on unlock the app resends the transcript and the backend
  immediately delivers the full analysis, strategies and exercises, then
  the dialogue continues without restriction.
- The old FREE_MESSAGE_LIMIT becomes MESSAGE_CAP (default 200/30 days),
  kept purely as an abuse backstop — it is not the paywall.
- WelcomeScreen removed; the app is now two views (Chat, Paywall).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0118DaxZR36RpnY524vRqx3z

apps/mobile/App.tsx

@@ -1,29 +1,45 @@
-import { useEffect, useState } from 'react';
+import { useState } from 'react';
 import { StatusBar } from 'expo-status-bar';
-import { getAccessToken } from './src/auth/session';
+import type { ChatMessage } from './src/api/client';
 import { ChatScreen } from './src/screens/ChatScreen';
 import { PaywallScreen } from './src/screens/PaywallScreen';
-import { WelcomeScreen } from './src/screens/WelcomeScreen';
-
-type View = 'loading' | 'welcome' | 'chat' | 'paywall';
 
 /**
- * Three views, no navigation library. The backend decides when the paywall
- * appears (HTTP 402 on /chat).
+ * Two views, no navigation library. The user lands directly in the chat —
+ * no registration before the first question. The backend decides the paywall
+ * moment (the analysis is ready); after unlock the conversation continues
+ * with the full analysis delivered immediately.
  */
 export default function App() {
-  const [view, setView] = useState<View>('loading');
-
-  useEffect(() => {
-    getAccessToken().then((token) => setView(token ? 'chat' : 'welcome'));
-  }, []);
+  const [view, setView] = useState<'chat' | 'paywall'>('chat');
+  const [messages, setMessages] = useState<ChatMessage[]>([]);
+  const [paywalled, setPaywalled] = useState(false);
+  const [deliverAnalysis, setDeliverAnalysis] = useState(false);
 
   return (
     <>
       <StatusBar style="dark" />
-      {view === 'welcome' && <WelcomeScreen onSignedIn={() => setView('chat')} />}
-      {view === 'chat' && <ChatScreen onLimitReached={() => setView('paywall')} />}
-      {view === 'paywall' && <PaywallScreen onSubscribed={() => setView('chat')} />}
+      {view === 'chat' && (
+        <ChatScreen
+          messages={messages}
+          setMessages={setMessages}
+          paywalled={paywalled}
+          onPaywallTriggered={() => setPaywalled(true)}
+          onContinueWithPremium={() => setView('paywall')}
+          deliverAnalysis={deliverAnalysis}
+          onAnalysisDelivered={() => setDeliverAnalysis(false)}
+        />
+      )}
+      {view === 'paywall' && (
+        <PaywallScreen
+          onSubscribed={() => {
+            setPaywalled(false);
+            setDeliverAnalysis(true);
+            setView('chat');
+          }}
+          onDismiss={() => setView('chat')}
+        />
+      )}
     </>
   );
 }