Record token usage per turn and show daily, weekly and all-time totals by host

Plugin/unraid/api/ai.php

@@ -134,6 +134,15 @@ if ($action === 'stats') {
     exit;
 }
 
+// ── tokens ────────────────────────────────────────────────────────────────────
+// Separate from stats rather than folded into it. stats is polled every 30 seconds by every
+// open tab; this reads a file that grows without bound between prunes. The totals only move
+// when a turn completes, and the page knows exactly when that happened, so it asks then.
+if ($action === 'tokens') {
+    echo json_encode(['ok' => true, 'tokens' => vv_ai_token_stats()]);
+    exit;
+}
+
 // ── poll ──────────────────────────────────────────────────────────────────────
 if ($action === 'poll') {
     $token = trim($_GET['token'] ?? '');