refactor: deprecate int32 (#7025)

* refactor: deprecate int32

* fix(db): reject legacy user quota schemas at startup

* fix(quota): enforce wallet bounds and saturating billing conversions

* fix(rate-limit): keep count*duration from wrapping int64

* fix: error message

web/src/features/usage-logs/types.ts

@@ -134,7 +134,7 @@ export interface LogOtherData {
     admin_role?: number
     auth_method?: 'session' | 'access_token' | string
     // Quota saturation marker: set when a quota conversion clamped at the
-    // int32 bound (overflow/underflow) or hit a NaN fallback while computing
+    // supported single-request bound (overflow/underflow) or hit a NaN fallback while computing
     // this request's charge. Admin-only (nested under admin_info).
     quota_saturation?: {
       op: string