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)/chat.tsx

@@ -1,6 +1,6 @@
-import { View, Text, TextInput, Pressable } from "react-native";
+import { View, Text, TextInput, Pressable, KeyboardAvoidingView, Platform, Keyboard } from "react-native";
 import currentTheme from "../../Themes";
-import { useState } from "react";
+import { useState, useRef, useEffect } from "react";
 import Header from "../../components/Header";
 import BaseBackground from "../../components/BaseBackground";
 import { FlashList } from "@shopify/flash-list";
@@ -31,6 +31,18 @@ type ChatInputProps = {
 
 const Chat = () => {
   const { messages, addMessage, updateMessage } = useChatStore();
+  const listRef = useRef<FlashList<MessageData>>(null);
+
+  useEffect(() => {
+    const keyboardDidShow = Keyboard.addListener("keyboardDidShow", scrollToEnd);
+    return () => keyboardDidShow.remove();
+  }, []);
+
+  const scrollToEnd = () => {
+    setTimeout(() => {
+      listRef.current?.scrollToEnd({ animated: true });
+    }, 100);
+  };
 
   const handleEventResponse = async (
     action: "confirm" | "reject",
@@ -61,6 +73,7 @@ const Chat = () => {
         conversationId: response.conversationId,
       };
       addMessage(botMessage);
+      scrollToEnd();
     } catch (error) {
       console.error(`Failed to ${action} event:`, error);
       // Revert on error
@@ -76,6 +89,7 @@ const Chat = () => {
       content: text,
     };
     addMessage(userMessage);
+    scrollToEnd();
 
     try {
       // Fetch server response
@@ -90,6 +104,7 @@ const Chat = () => {
         conversationId: response.conversationId,
       };
       addMessage(botMessage);
+      scrollToEnd();
     } catch (error) {
       console.error("Failed to send message:", error);
     }
@@ -98,30 +113,38 @@ const Chat = () => {
   return (
     <BaseBackground>
       <ChatHeader />
-      <FlashList
-        data={messages}
-        renderItem={({ item }) => (
-          <ChatMessage
-            side={item.side}
-            content={item.content}
-            proposedChange={item.proposedChange}
-            respondedAction={item.respondedAction}
-            onConfirm={() =>
-              handleEventResponse(
-                "confirm",
-                item.id,
-                item.conversationId!,
-                item.proposedChange,
-              )
-            }
-            onReject={() =>
-              handleEventResponse("reject", item.id, item.conversationId!)
-            }
-          />
-        )}
-        keyExtractor={(item) => item.id}
-      />
-      <ChatInput onSend={handleSend} />
+      <KeyboardAvoidingView
+        behavior={Platform.OS === "ios" ? "padding" : "height"}
+        style={{ flex: 1 }}
+      >
+        <FlashList
+          ref={listRef}
+          data={messages}
+          renderItem={({ item }) => (
+            <ChatMessage
+              side={item.side}
+              content={item.content}
+              proposedChange={item.proposedChange}
+              respondedAction={item.respondedAction}
+              onConfirm={() =>
+                handleEventResponse(
+                  "confirm",
+                  item.id,
+                  item.conversationId!,
+                  item.proposedChange,
+                )
+              }
+              onReject={() =>
+                handleEventResponse("reject", item.id, item.conversationId!)
+              }
+            />
+          )}
+          keyExtractor={(item) => item.id}
+          keyboardDismissMode="interactive"
+          keyboardShouldPersistTaps="handled"
+        />
+        <ChatInput onSend={handleSend} />
+      </KeyboardAvoidingView>
     </BaseBackground>
   );
 };