restore the code editor screen, drop the dead theme picker, unshadow AppRegistry

Three unrelated type errors that each pointed at something actually broken:

- Dashboard.CodeEditor was deleted in ab03b17 ("Projects") while the
  /code-editor route and the dock's Editor item kept pointing at it, so the
  route rendered undefined. Screen restored.

- Appearance.tsx imported 'themes', a workspace deleted in 0746844. Nothing
  reads settings.appearance.colorTheme and no theme CSS survives, so the picker
  was writing a value with no consumer. Removed it and the setting; colorMode
  stays, it is live.

- officerdev exported both a component and a type named AppRegistry, so
  `import { AppRegistry }` resolved to the type and <AppRegistry /> failed to
  typecheck. Renamed the Record type to AppRegistryMap.

Also declares "*.css" so side-effect stylesheet imports resolve.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

bun-env.d.ts

@@ -8,6 +8,10 @@ declare module "*.svg" {
   export = path;
 }
 
+// Plain stylesheets are imported for their side effect only; the bundler injects them. The more
+// specific "*.module.css" declaration below still wins for CSS modules.
+declare module "*.css";
+
 declare module "*.module.css" {
   /**
    * A record of class names to their corresponding CSS module classes