Add SOLD OUT badge and improve deployment docs

- Add SOLD OUT overlay on car detail page image
- Add SOLD OUT badge next to car name
- Add Sold Out status in Admin Cars detail view
- Add soldout field to Car TypeScript interface
- Create PRODUCTION_VALUES.md for deployment reference
- Update CLAUDE.md with CRITICAL deployment section
- Update TROUBLESHOOTING.md with recurring errors

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

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

frontend/src/types/index.ts

@@ -48,6 +48,7 @@ export interface Car {
   dealer_description_mn?: string;
   dealer_description_ru?: string;
   status: string;
+  soldout?: boolean;
   created_at: string;
   updated_at: string;
   maker?: CarMaker;