feat: add configurable sandbox mode setting

Add a global setting to enable/disable sandbox mode for Claude Agent SDK.
This allows users to control sandbox behavior based on their authentication
setup and system compatibility.

Changes:
- Add enableSandboxMode to GlobalSettings (default: true)
- Add sandbox mode checkbox in Claude settings UI
- Wire up setting through app store and settings service
- Update createChatOptions and createAutoModeOptions to use setting
- Add getEnableSandboxModeSetting helper function
- Remove hardcoded sandbox configuration from ClaudeProvider
- Add detailed logging throughout agent execution flow

The sandbox mode requires API key or OAuth token authentication. Users
experiencing issues with CLI-only auth can disable it in settings.

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

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

apps/ui/src/components/views/settings-view.tsx

@@ -50,6 +50,8 @@ export function SettingsView() {
     setValidationModel,
     autoLoadClaudeMd,
     setAutoLoadClaudeMd,
+    enableSandboxMode,
+    setEnableSandboxMode,
   } = useAppStore();
 
   // Hide usage tracking when using API key (only show for Claude Code CLI users)
@@ -108,6 +110,8 @@ export function SettingsView() {
             <ClaudeMdSettings
               autoLoadClaudeMd={autoLoadClaudeMd}
               onAutoLoadClaudeMdChange={setAutoLoadClaudeMd}
+              enableSandboxMode={enableSandboxMode}
+              onEnableSandboxModeChange={setEnableSandboxMode}
             />
             {showUsageTracking && <ClaudeUsageSection />}
           </div>