Add exportState and moduleSnapshot helpers across all module categories.

Fifth pass: complete measurement modules (sla-budget, histogram-gossip) with moduleSnapshot/toJSON; stats-exporter exportSnapshot; exportState() alias on modules with standard snapshot serialization.

Co-authored-by: Cursor <[email protected]>

supercomputer/hyper-p2p-gpu-slot/index.js

@@ -126,6 +126,10 @@ class HyperP2PGpuSlot extends EventEmitter {
     return this.snapshot()
   }
 
+  exportState () {
+    return this.toJSON()
+  }
+
   async ready () {
     if (this.swarm || !this.topic) return this
     await initModuleSwarm(this, {