test(auth,payments,subs): add 58 unit tests for critical auth, payment, and subscription paths

Cover auth handlers (RegisterUser, LoginUser, RefreshToken), TokenService
(token rotation, reuse attack detection), payment callback edge cases
(duplicate/concurrent callbacks, multi-provider), subscription lifecycle
transitions (expire, pastDue, renew), and throttler proxy guard.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

pnpm-lock.yaml

@@ -18,6 +18,9 @@ importers:
       '@playwright/test':
         specifier: ^1.59.1
         version: 1.59.1
+      '@types/pg':
+        specifier: ^8.20.0
+        version: 8.20.0
       dependency-cruiser:
         specifier: ^17.3.10
         version: 17.3.10
@@ -45,6 +48,9 @@ importers:
       lint-staged:
         specifier: ^16.4.0
         version: 16.4.0
+      pg:
+        specifier: ^8.20.0
+        version: 8.20.0
       prettier:
         specifier: ^3.8.1
         version: 3.8.1