refactor(pop): isolate new shell, add super-admin entry, drop /pop fallback

- per-company PopShell copies under (main)/COMPANY_*/pop/_components/common/
  (no longer imports @/components/pop/hardcoded/PopShell)
- new components/pop/shell/CompanySwitchModal for new POP entry
- AppLayout: SUPER_ADMIN POP-mode toggle + company-select modal flow
- usePopSettings: handle /COMPANY_X/pop/<tail> URLs (extractScreenKey)
- authController + AppLayout: drop legacy /pop fallback;
  use /\${companyCode}/pop/main when childMenus>1 lacks [POP_LANDING]

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend-node/src/controllers/authController.ts

@@ -103,7 +103,10 @@ export class AuthController {
           } else if (popResult.childMenus.length === 1) {
             popLandingPath = popResult.childMenus[0].menu_url;
           } else if (popResult.childMenus.length > 1) {
-            popLandingPath = "/pop";
+            const userCompanyCode = loginResult.userInfo.companyCode;
+            if (userCompanyCode && userCompanyCode !== "*") {
+              popLandingPath = `/${userCompanyCode}/pop/main`;
+            }
           }
           logger.debug(`POP 랜딩 경로: ${popLandingPath}`);