feat: Add OIDC authentication with Authentik integration

- Add OIDC login flow with Authentik provider
- Implement session-based auth with Redis store
- Add avatar display from OIDC claims
- Fix input field performance with react-textarea-autosize
- Stabilize callbacks to prevent unnecessary re-renders
- Fix history loading to skip empty session files
- Add 2-row default height for input textarea

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/ChatPanel.jsx

@@ -1,4 +1,4 @@
-import { memo, useCallback, useMemo } from 'react';
+import { memo, useCallback, useMemo, useRef } from 'react';
 import { MessageList } from './MessageList';
 import { ChatInput } from './ChatInput';
 import { StatusBar } from './StatusBar';
@@ -94,25 +94,36 @@ const ErrorBanner = memo(function ErrorBanner({ error, onClear }) {
 
 // Use a separate hook that memoizes everything to prevent unnecessary re-renders
 function useMemoizedSession(sessionId) {
-  const manager = useSessionManager();
-  const session = manager.sessions[sessionId];
-  const messages = manager.sessionMessages[sessionId] || [];
+  const {
+    sessions,
+    sessionMessages,
+    startClaudeSession,
+    stopClaudeSession,
+    sendMessage,
+    stopGeneration,
+    clearMessages,
+    changePermissionMode,
+    respondToPermission,
+  } = useSessionManager();
+
+  const session = sessions[sessionId];
+  const messages = sessionMessages[sessionId] || [];
 
   // Memoize the combined session object
   const sessionWithMessages = useMemo(() => {
     return session ? { ...session, messages } : null;
   }, [session, messages]);
 
-  // Memoize all action functions
+  // Memoize all action functions - use individual functions as deps, not the whole manager
   const actions = useMemo(() => ({
-    start: () => manager.startClaudeSession(sessionId),
-    stop: () => manager.stopClaudeSession(sessionId),
-    send: (msg, attachments) => manager.sendMessage(sessionId, msg, attachments),
-    stopGeneration: () => manager.stopGeneration(sessionId),
-    clearMessages: () => manager.clearMessages(sessionId),
-    changePermissionMode: (mode) => manager.changePermissionMode(sessionId, mode),
-    respondToPermission: (reqId, allow) => manager.respondToPermission(sessionId, reqId, allow),
-  }), [sessionId, manager]);
+    start: () => startClaudeSession(sessionId),
+    stop: () => stopClaudeSession(sessionId),
+    send: (msg, attachments) => sendMessage(sessionId, msg, attachments),
+    stopGeneration: () => stopGeneration(sessionId),
+    clearMessages: () => clearMessages(sessionId),
+    changePermissionMode: (mode) => changePermissionMode(sessionId, mode),
+    respondToPermission: (reqId, allow) => respondToPermission(sessionId, reqId, allow),
+  }), [sessionId, startClaudeSession, stopClaudeSession, sendMessage, stopGeneration, clearMessages, changePermissionMode, respondToPermission]);
 
   return { session: sessionWithMessages, ...actions };
 }
@@ -134,11 +145,22 @@ export const ChatPanel = memo(function ChatPanel({ sessionId }) {
     // For now, errors auto-clear on next action
   }, []);
 
+  // Use refs for callbacks to keep them stable across re-renders
+  const sendRef = useRef(send);
+  sendRef.current = send;
+  const stopGenerationRef = useRef(stopGeneration);
+  stopGenerationRef.current = stopGeneration;
+
+  // These callbacks never change identity, preventing ChatInput re-renders
   const handleSendMessage = useCallback((message, attachments = []) => {
     if (message.trim() || attachments.length > 0) {
-      send(message, attachments);
+      sendRef.current(message, attachments);
     }
-  }, [send]);
+  }, []);
+
+  const handleStopGeneration = useCallback(() => {
+    stopGenerationRef.current();
+  }, []);
 
   if (!session) {
     return (
@@ -178,7 +200,7 @@ export const ChatPanel = memo(function ChatPanel({ sessionId }) {
       {/* Input - memoized props to prevent re-renders during streaming */}
       <MemoizedChatInput
         onSend={handleSendMessage}
-        onStop={stopGeneration}
+        onStop={handleStopGeneration}
         disabled={!session.active}
         isProcessing={session.isProcessing}
         sessionId={session.claudeSessionId}