Fix: Resolve UI/UX issues and improve user experience

- Configure Firebase Auth with AsyncStorage persistence
- Fix 'Text strings must be rendered within <Text>' error in navigation
- Improve bottom tab bar: iOS style with blur effect, better height, rounded corners
- Fix Dashboard quick action buttons to open transaction modal directly
- Add auto-open modal when navigating from Dashboard
- Improve selection visibility in modals (type selector and categories)
- Add amount validation: only positive numbers, max 2 decimals
- Add padding to Dashboard content to avoid tab bar overlap
- Apply same fixes to both Transaction and Subscription screens

src/screens/TransactionScreen.tsx

@@ -17,7 +17,7 @@ import { TransactionCard } from '../components/TransactionCard';
 import { InputText } from '../components/InputText';
 import { Button } from '../components/Button';
 
-export const TransactionScreen = ({ route }: any) => {
+export const TransactionScreen = ({ route, navigation }: any) => {
   const { user } = useAuth();
   const [transactions, setTransactions] = useState<Transaction[]>([]);
   const [categories, setCategories] = useState<Category[]>([]);
@@ -48,6 +48,18 @@ export const TransactionScreen = ({ route }: any) => {
     return () => unsubscribe();
   }, [user]);
 
+  // Ouvrir le modal automatiquement si on vient du Dashboard
+  useEffect(() => {
+    if (route?.params?.openModal) {
+      setModalVisible(true);
+      if (route.params.type) {
+        setType(route.params.type);
+      }
+      // Réinitialiser le paramètre
+      navigation.setParams({ openModal: false });
+    }
+  }, [route?.params]);
+
   const loadCategories = async () => {
     if (!user) return;
 
@@ -218,7 +230,16 @@ export const TransactionScreen = ({ route }: any) => {
                 label="Montant (€)"
                 placeholder="0.00"
                 value={amount}
-                onChangeText={setAmount}
+                onChangeText={(text) => {
+                  // Permettre uniquement les chiffres et un point décimal
+                  const cleaned = text.replace(/[^0-9.]/g, '');
+                  // Empêcher plusieurs points
+                  const parts = cleaned.split('.');
+                  if (parts.length > 2) return;
+                  // Limiter à 2 décimales
+                  if (parts[1] && parts[1].length > 2) return;
+                  setAmount(cleaned);
+                }}
                 keyboardType="decimal-pad"
               />
 
@@ -356,7 +377,8 @@ const styles = StyleSheet.create({
     alignItems: 'center'
   },
   typeButtonActive: {
-    borderWidth: 2
+    borderWidth: 3,
+    backgroundColor: '#F0F7FF'
   },
   expenseButton: {
     borderColor: '#FF6B6B'
@@ -367,10 +389,11 @@ const styles = StyleSheet.create({
   typeButtonText: {
     fontSize: 16,
     fontWeight: '600',
-    color: '#666'
+    color: '#999'
   },
   typeButtonTextActive: {
-    color: '#333'
+    color: '#333',
+    fontWeight: '700'
   },
   label: {
     fontSize: 14,
@@ -396,7 +419,13 @@ const styles = StyleSheet.create({
   },
   categoryItemActive: {
     backgroundColor: '#FFF',
-    borderWidth: 2
+    borderWidth: 3,
+    transform: [{ scale: 1.05 }],
+    shadowColor: '#000',
+    shadowOffset: { width: 0, height: 2 },
+    shadowOpacity: 0.2,
+    shadowRadius: 4,
+    elevation: 4
   },
   categoryIcon: {
     fontSize: 28,
@@ -405,6 +434,7 @@ const styles = StyleSheet.create({
   categoryName: {
     fontSize: 11,
     color: '#666',
+    fontWeight: '600',
     textAlign: 'center'
   },
   submitButton: {