feat: improve chat keyboard handling and MonthSelector memory efficiency

- Add KeyboardAvoidingView with platform-specific behavior to chat screen
- Implement auto-scroll to end on new messages and keyboard show
- Configure keyboardDismissMode and keyboardShouldPersistTaps for better UX
- Lazy-load MonthSelector data only when modal opens, clear on close
- Add .env to gitignore

apps/client/src/app/(tabs)/calendar.tsx

@@ -323,16 +323,7 @@ const MonthSelector = ({
   const listRef = useRef<React.ComponentRef<typeof FlashList<MonthItem>>>(null);
   const INITIAL_RANGE = 12; // 12 months before and after current
 
-  const [monthSelectorData, setMonthSelectorData] = useState<MonthItem[]>(() =>
-    generateMonths(currentYear, currentMonthIndex, INITIAL_RANGE),
-  );
-
-  // Reset data when current month changes
-  useEffect(() => {
-    setMonthSelectorData(
-      generateMonths(currentYear, currentMonthIndex, INITIAL_RANGE),
-    );
-  }, [currentYear, currentMonthIndex]);
+  const [monthSelectorData, setMonthSelectorData] = useState<MonthItem[]>([]);
 
   const appendMonths = (direction: "start" | "end", count: number) => {
     setMonthSelectorData((prevData) => {
@@ -378,6 +369,10 @@ const MonthSelector = ({
 
   useEffect(() => {
     if (modalVisible) {
+      // Generate fresh data centered on current month
+      setMonthSelectorData(
+        generateMonths(currentYear, currentMonthIndex, INITIAL_RANGE),
+      );
       Animated.timing(heightAnim, {
         toValue: 200,
         duration: 200,
@@ -385,8 +380,10 @@ const MonthSelector = ({
       }).start();
     } else {
       heightAnim.setValue(0);
+      // Clear data when closing
+      setMonthSelectorData([]);
     }
-  }, [modalVisible, heightAnim]);
+  }, [modalVisible, heightAnim, currentYear, currentMonthIndex]);
 
   const renderItem = ({ item }: { item: MonthItem }) => (
     <Pressable