refactor(cli): simplify architecture with auth store and MessageBlock

split

- Create auth-store.ts for centralized authentication state management -
Reduce Chat component props from 11 to 8 (remove auth prop drilling) -
Split 900-line MessageBlock into 4 focused modules: - message-block.tsx
(220 lines) - message orchestration - blocks/agent-body.tsx (280 lines)
- agent rendering - blocks/blocks-renderer.tsx (280 lines) - block
iteration - utils/block-tree.ts - shared block manipulation utilities -
Extract block manipulation logic to reusable utilities - Eliminate 100+
lines of duplicate recursive block code

All tests pass (231/231) and typechecks clean.

Author: brandonkachen

cli/src/app.tsx

@@ -60,13 +60,7 @@ export const App = ({
     })),
   )
 
-  const {
-    isAuthenticated,
-    setIsAuthenticated,
-    setUser,
-    handleLoginSuccess,
-    logoutMutation,
-  } = useAuthState({
+  const { isAuthenticated, handleLoginSuccess, logout } = useAuthState({
     requireAuth,
     hasInvalidCredentials,
     inputRef,
@@ -221,12 +215,9 @@ export const App = ({
       loadedAgentsData={loadedAgentsData}
       validationErrors={validationErrors}
       fileTree={fileTree}
-      inputRef={inputRef}
-      setIsAuthenticated={setIsAuthenticated}
-      setUser={setUser}
-      logoutMutation={logoutMutation}
       continueChat={continueChat}
       continueChatId={continueChatId}
+      logout={logout}
     />
   )
 }