fix(08): WR-02 — CPU3 demands the ladder only when the gitignored binary is present

- the graph binary is NOT committed: routing/data/.gitignore ignores
  *.bin (git check-ignore verified) — forks rebuild their own
  (docs/ROAD-GRAPH.md), so the old assertion message was factually false
- CPU3 now mirrors CPU4's law: absent binary -> honest SKIP (not a
  failure); the run-the-ladder assertions fire only when it is present
- reason text aligned with reality: 'gitignored fork-rebuildable artifact'

scripts/test/budget-audit.test.mjs

@@ -101,10 +101,20 @@ await test("CPU2 the ladder is RE-RUN (the gate references measure-route-cpu) an
   assert.ok(src.includes("P95_BUDGET_MS = 8"), "the gate must carry the 8 ms product budget constant");
 });
 
-await test("CPU3 on the current tree the ladder runs, the measured p95 is printed against the 8 ms budget and the 10 ms free ceiling, and the child's own GATE line is carried", async () => {
+await test("CPU3 when the local graph binary is present the ladder runs, the measured p95 is printed against the 8 ms budget and the 10 ms free ceiling, and the child's own GATE line is carried", async () => {
   const m = await import(gatesUrl);
+  // The binary is a GITIGNORED FORK-REBUILDABLE ARTIFACT, not a committed
+  // file (routing/data/.gitignore ignores *.bin; docs/ROAD-GRAPH.md — forks
+  // build + upload their own). On a fresh fork its absence is the legal
+  // notRun class — CPU4's law — so the real-graph leg SKIPs honestly and is
+  // NEVER a failure; the ladder is demanded only when the binary is present.
+  const graphPresent = existsSync(path.join(ROOT, "routing", "data", "kl-roadgraph.v1.bin"));
+  if (!graphPresent) {
+    console.log("    SKIP — CPU3 needs the gitignored local binary (build it first: node routing/scripts/build-road-graph.mjs); not a failure");
+    return;
+  }
   const r = await m.runCpuLadderGate();
-  assert.equal(r.notRun, undefined, "the graph binary is committed — the ladder must run, not skip");
+  assert.equal(r.notRun, undefined, "the binary is present — the ladder must run, not skip");
   assert.equal(r.pass, true, `the measured state must sit inside the documented accepted c3 band: ${r.evidence}`);
   assert.match(r.evidence, /p95 \d+(\.\d+)? ms/, "the measured p95 must be printed");
   assert.match(r.evidence, /8 ms/, "the 8 ms product budget must be printed beside the measurement");