feat: add AI Dental Shopping section with sidebar nav and Login Info page

- Add AI Dental Shopping to sidebar with Search/Tag and Login Info sub-pages
- Build full-stack Login Info CRUD: save vendor name, website, username, password per user
- Add ShoppingVendor Prisma model, run db push, regenerate client and Zod schemas
- Add storage layer, REST API at /api/shopping-vendors/, and frontend table with add/edit/delete modal

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/db/shared/schemas/variants/result/index.ts

@@ -14,6 +14,7 @@ export { ClaimResultSchema } from './Claim.result';
 export { ServiceLineResultSchema } from './ServiceLine.result';
 export { ClaimFileResultSchema } from './ClaimFile.result';
 export { InsuranceCredentialResultSchema } from './InsuranceCredential.result';
+export { ShoppingVendorResultSchema } from './ShoppingVendor.result';
 export { PdfGroupResultSchema } from './PdfGroup.result';
 export { PdfFileResultSchema } from './PdfFile.result';
 export { PaymentResultSchema } from './Payment.result';