fix(cpg): the instrument reports on itself -- census failure fails the build, overlays and heap are checked

Three checks for three findings that were each silently wrong for a day (task 5.13). A clean build whose
census cannot be taken inside the query timeout is a failed build, by name: every later query would time
out and read as "nothing here", and the launcher fallback no longer rebuilds the same graph without
asking again. The census now carries the graph's saved overlays and the worker JVM's actual heap, and the
backend warns when the dataflow layer is missing (every batch would recompute it) or the heap is not the
configured one (the knob is not reaching the JVM that matters). An empty tree counts as complete, not as
a failed count.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

src/openultrasast/cpg/queries/census.sc

@@ -8,11 +8,25 @@
 // This matters because acting on the warning alone is destructive: it makes the driver split a repository
 // into shards that cannot see each other's flows, and a two-file WordPress pair lost its CVE that way.
 //
+// It also reports two facts about the INSTRUMENT that were each, once, wrong for a day without anything
+// saying so (contributor-scan 5.13): which overlays the graph carries, because a graph without its
+// dataflow layer saved has it recomputed by every query batch; and the heap the worker JVM actually got,
+// because `-J-Xmx` reaches only the launcher and the configured heap governed nothing until that was seen.
+//
 // Parameters: cpgFile.
-// Output: fenced JSON {files, methods}.
+// Output: fenced JSON {files, methods, overlays, maxHeapMB}.
 @main def exec(cpgFile: String) = {
   importCpg(cpgFile)
   println("---OUSAST-CPG-BEGIN---")
-  println(ujson.write(ujson.Obj("files" -> cpg.file.size.toString, "methods" -> cpg.method.size.toString)))
+  println(
+    ujson.write(
+      ujson.Obj(
+        "files"     -> cpg.file.size.toString,
+        "methods"   -> cpg.method.size.toString,
+        "overlays"  -> cpg.metaData.overlays.l.flatten.mkString(","),
+        "maxHeapMB" -> (Runtime.getRuntime.maxMemory / 1048576).toString
+      )
+    )
+  )
   println("---OUSAST-CPG-END---")
 }