feat: Apple Watch app + Paywall + Privacy Policy + rebranding

## Major Features
- Apple Watch companion app (6 phases complete)
  - WatchConnectivity iPhone ↔ Watch
  - HealthKit integration (HR, calories)
  - SwiftUI premium UI
  - 9 complication types
  - Always-On Display support

- Paywall screen with RevenueCat integration
- Privacy Policy screen
- App rebranding: tabatago → TabataFit
- Bundle ID: com.millianlmx.tabatafit

## Changes
- New: ios/TabataFit Watch App/ (complete Watch app)
- New: app/paywall.tsx (subscription UI)
- New: app/privacy.tsx (privacy policy)
- New: src/features/watch/ (Watch sync hooks)
- New: admin-web/ (admin dashboard)
- Updated: app.json, package.json (branding)
- Updated: profile.tsx (paywall + privacy links)
- Updated: i18n translations (EN/FR/DE/ES)
- New: app icon 1024x1024

## Watch App Files
- TabataFitWatchApp.swift (entry point)
- ContentView.swift (premium UI)
- HealthKitManager.swift (HR + calories)
- WatchSessionManager.swift (communication)
- Complications/ (WidgetKit)
- UserDefaults+Shared.swift (data sharing)

app/admin/login.tsx

@@ -0,0 +1,124 @@
+import { useState } from 'react'
+import {
+  View,
+  Text,
+  TextInput,
+  TouchableOpacity,
+  StyleSheet,
+  ActivityIndicator,
+} from 'react-native'
+import { useAdminAuth } from '../../src/admin/components/AdminAuthProvider'
+
+export default function AdminLoginScreen() {
+  const [email, setEmail] = useState('')
+  const [password, setPassword] = useState('')
+  const [error, setError] = useState('')
+  const { signIn, isLoading } = useAdminAuth()
+
+  const handleLogin = async () => {
+    if (!email || !password) {
+      setError('Please enter both email and password')
+      return
+    }
+
+    setError('')
+    try {
+      await signIn(email, password)
+    } catch (err) {
+      setError(err instanceof Error ? err.message : 'Login failed')
+    }
+  }
+
+  return (
+    <View style={styles.container}>
+      <View style={styles.card}>
+        <Text style={styles.title}>TabataFit Admin</Text>
+        <Text style={styles.subtitle}>Sign in to manage content</Text>
+
+        {error ? <Text style={styles.errorText}>{error}</Text> : null}
+
+        <TextInput
+          style={styles.input}
+          placeholder="Email"
+          placeholderTextColor="#666"
+          value={email}
+          onChangeText={setEmail}
+          autoCapitalize="none"
+          keyboardType="email-address"
+        />
+
+        <TextInput
+          style={styles.input}
+          placeholder="Password"
+          placeholderTextColor="#666"
+          value={password}
+          onChangeText={setPassword}
+          secureTextEntry
+        />
+
+        <TouchableOpacity
+          style={styles.button}
+          onPress={handleLogin}
+          disabled={isLoading}
+        >
+          {isLoading ? (
+            <ActivityIndicator color="#000" />
+          ) : (
+            <Text style={styles.buttonText}>Sign In</Text>
+          )}
+        </TouchableOpacity>
+      </View>
+    </View>
+  )
+}
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+    backgroundColor: '#000',
+    justifyContent: 'center',
+    alignItems: 'center',
+    padding: 20,
+  },
+  card: {
+    backgroundColor: '#1C1C1E',
+    borderRadius: 16,
+    padding: 32,
+    width: '100%',
+    maxWidth: 400,
+  },
+  title: {
+    fontSize: 28,
+    fontWeight: 'bold',
+    color: '#fff',
+    marginBottom: 8,
+  },
+  subtitle: {
+    fontSize: 16,
+    color: '#999',
+    marginBottom: 24,
+  },
+  errorText: {
+    color: '#FF3B30',
+    marginBottom: 16,
+  },
+  input: {
+    backgroundColor: '#2C2C2E',
+    borderRadius: 8,
+    padding: 16,
+    marginBottom: 16,
+    color: '#fff',
+    fontSize: 16,
+  },
+  button: {
+    backgroundColor: '#FF6B35',
+    borderRadius: 8,
+    padding: 16,
+    alignItems: 'center',
+  },
+  buttonText: {
+    color: '#000',
+    fontSize: 16,
+    fontWeight: 'bold',
+  },
+})