fix: refcount StatsCache keys, keep registrations across config change, and tidy GPU/usage render paths

src/lib/runtime.ts

@@ -12,7 +12,6 @@ class Runtime {
   private feed?: EventFeed;
   private poller?: MetricsPoller;
   private statsCache?: StatsCache;
-  private statsUnsub?: () => void;
   private listeners = new Set<() => void>();
 
   ensureConnections(cfg: LlamaSwapConfig): void {
@@ -22,9 +21,7 @@ class Runtime {
       this.poller?.stop();
       this.feed = undefined;
       this.poller = undefined;
-      this.statsUnsub?.();
-      this.statsCache = undefined;
-      this.statsUnsub = undefined;
+      this.statsCache?.setConfig(cfg);
       this.cfg = cfg;
     }
     if (!this.feed) {
@@ -46,7 +43,7 @@ class Runtime {
     }
     if (!this.statsCache) {
       this.statsCache = new StatsCache(cfg);
-      this.statsUnsub = this.statsCache.onChange(() => this.emit());
+      this.statsCache.onChange(() => this.emit());
     }
   }