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/components/settings/SettingsPanel.tsx

@@ -1,5 +1,6 @@
 import ApiKeyInput from "./ApiKeyInput";
 import DockerSettings from "./DockerSettings";
+import AwsSettings from "./AwsSettings";
 
 export default function SettingsPanel() {
   return (
@@ -9,6 +10,7 @@ export default function SettingsPanel() {
       </h2>
       <ApiKeyInput />
       <DockerSettings />
+      <AwsSettings />
     </div>
   );
 }