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]>

pear-platform/hyper-pear-preflight-sync/index.js

@@ -151,6 +151,10 @@ class HyperPearPreflightSync extends EventEmitter {
     return this.snapshot()
   }
 
+  exportState () {
+    return this.toJSON()
+  }
+
   startBatch (entries) {
     if (!Array.isArray(entries)) throw new Error('entries array required')
     return entries.map((e) => this.start(e.target, e.meta || {}))