feat: surface cached token counts in /status output (openclaw#21248) thanks @vishaltandale00

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

Co-authored-by: vishaltandale00 <9222298+vishaltandale00@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/commands/agent/session-store.ts

@@ -76,6 +76,8 @@ export async function updateSessionStoreAfterAgentRun(params: {
     next.outputTokens = output;
     next.totalTokens = totalTokens;
     next.totalTokensFresh = true;
+    next.cacheRead = usage.cacheRead ?? 0;
+    next.cacheWrite = usage.cacheWrite ?? 0;
   }
   if (compactionsThisRun > 0) {
     next.compactionCount = (entry.compactionCount ?? 0) + compactionsThisRun;