feat(billing): make metering formula admin-configurable

Allow margin/FX/cost-mode knobs to be overridden via h5_billing_admin_config so memind_adm can adjust DeepSeek billing without editing env.

Co-authored-by: Cursor <cursoragent@cursor.com>

tkmind-proxy.mjs

@@ -1138,6 +1138,7 @@ export function createTkmindProxy({
   llmProviderService,
   localFetchAsset,
   subscriptionService,
+  billingConfigService = null,
   sessionSnapshotService,
   conversationMemoryService,
   memoryV2,
@@ -2097,6 +2098,9 @@ export function createTkmindProxy({
     return resolveBillingTokenState(tokenStateRaw, {
       sessionId,
       fetchSession: fetchSessionBillingCost,
+      loadEstimateConfig: billingConfigService?.getEffectiveCostEstimateConfig
+        ? () => billingConfigService.getEffectiveCostEstimateConfig()
+        : null,
     });
   }