feat(chrome): hand snapshots to context mode

pi-chrome/test-suite/challenges/39-strict-csp-fallback.js

@@ -0,0 +1,27 @@
+Challenge.init({ id: "strict-csp-fallback", instructions: "use screenshot/coordinates; click CSP TARGET" });
+
+const btn = document.getElementById("cspTarget");
+btn.style.cssText = [
+  "position:fixed",
+  "left:220px",
+  "top:220px",
+  "width:180px",
+  "height:72px",
+  "font:700 16px system-ui",
+  "background:#1f7a1f",
+  "color:white",
+  "border:0",
+  "border-radius:10px",
+  "box-shadow:0 0 0 4px rgba(31,122,31,.25)"
+].join(";");
+
+document.getElementById("cspTarget").addEventListener("click", (e) => {
+  const r = btn.getBoundingClientRect();
+  const bad = [];
+  if (!e.isTrusted) bad.push("click isTrusted=false");
+  if (e.clientX < r.left || e.clientX > r.right || e.clientY < r.top || e.clientY > r.bottom) {
+    bad.push(`click coordinates ${e.clientX},${e.clientY} outside target rect ${Math.round(r.left)},${Math.round(r.top)},${Math.round(r.right)},${Math.round(r.bottom)}`);
+  }
+  if (bad.length) Challenge.fail(...bad);
+  else Challenge.pass("strict CSP page completed via trusted viewport click");
+});