feat(plugins): expose llm input/output hook payloads (openclaw#16724) thanks @SecondThread

Verified:
- pnpm build
- pnpm check
- pnpm test:macmini

Co-authored-by: SecondThread <18317476+SecondThread@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/infra/diagnostic-events.ts

@@ -22,6 +22,13 @@ export type DiagnosticUsageEvent = DiagnosticBaseEvent & {
     promptTokens?: number;
     total?: number;
   };
+  lastCallUsage?: {
+    input?: number;
+    output?: number;
+    cacheRead?: number;
+    cacheWrite?: number;
+    total?: number;
+  };
   context?: {
     limit?: number;
     used?: number;