test: opt-in gate for live-playwright ML tests; ios-qa build hygiene

security-live-playwright's L4 tests dlopen onnxruntime inside a bun
--parallel worker whenever the dev box has a warm model cache — the
source of the intermittent 'panic: Segmentation fault' + crashed-worker
retries (and likely the residual run wedges). Same SECURITY_BENCH=1
opt-in as security-bench.test.ts; the L1-L3 tests in the file still run
everywhere.

Also: gitignore the ios-qa gen-accessors-tool Swift .build/ output (a
side-effect of running its tests that kept polluting git status) and
commit its Package.resolved so tool builds resolve reproducibly.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ios-qa/scripts/gen-accessors-tool/Package.resolved

@@ -0,0 +1,14 @@
+{
+  "pins" : [
+    {
+      "identity" : "swift-syntax",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/swiftlang/swift-syntax.git",
+      "state" : {
+        "revision" : "2bc86522d115234d1f588efe2bcb4ce4be8f8b82",
+        "version" : "510.0.3"
+      }
+    }
+  ],
+  "version" : 2
+}