Phase 2 backend: Google Wallet pass + profile contact form

- cardclaws-wallet::google — inline GenericObject + RS256 `savetowallet` JWT
  (Rs256Signer via jsonwebtoken; FakeGoogleSigner test double)
- POST /v1/cards/{id}/wallet/google → { saveUrl }
- POST /v1/profile/{handle}/contact — validate, rate-limit, record
  contact_form_submission, email the owner (HTML-escaped, Resend)
- WalletConfig gains google issuer id + service account email

84 backend tests; fmt + clippy clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

cardclaws-backend/crates/cardclaws-api/src/services/mod.rs

@@ -1,6 +1,7 @@
 pub mod analytics_service;
 pub mod auth_service;
 pub mod card_service;
+pub mod profile_service;
 pub mod share_service;
 pub mod vcard;
 pub mod wallet_service;