Add container registry pull, image source settings, and global AWS config

Support pulling images from registry (default: repo.anhonesthost.net/cybercovellc/triple-c/triple-c-sandbox:latest),
local builds, or custom images via a new settings UI. Add global AWS configuration
(config path auto-detect, profile picker, region) that serves as defaults overridable
per-project for Bedrock auth.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src/App.tsx

@@ -10,12 +10,13 @@ import { useAppState } from "./store/appState";
 
 export default function App() {
   const { checkDocker, checkImage } = useDocker();
-  const { checkApiKey } = useSettings();
+  const { checkApiKey, loadSettings } = useSettings();
   const { refresh } = useProjects();
   const { sessions, activeSessionId } = useAppState();
 
   // Initialize on mount
   useEffect(() => {
+    loadSettings();
     checkDocker();
     checkImage();
     checkApiKey();