fix(javascript): read utilityProcess.fork options from the argv slot (#6280)

Electron's utilityProcess.fork(modulePath[, args][, options]) treats a
non-array object in the second argument as the options and ignores the
third. The static extractor only read the third argument, so
`fork("./worker.js", { serviceName })` lost the declared name while
reporting exact, complete coverage, and an object in the second slot let
an ignored third argument supply the name.

Move the optional-argv options selection that child_process already used
into the shared expression-shape owner and reuse it for utility
processes. Unproven argv shapes, spreads and identifier options remain
unknown with partial coverage; nullish options or a nullish serviceName
declare no name, matching Electron's runtime checks.

Fixes #6208

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/domain/javascript/javascriptSemanticExpressionShapes.ts

@@ -24,6 +24,11 @@ import { traverseJavaScriptAst } from "./javascriptSemanticTraversal.js";
 import { javaScriptRuntimeContext } from "./javascriptSourceParser.js";
 
 type Shape = "array" | "callback" | "unknown";
+
+/** Bounded argument-shape queries shared by call-signature owners. */
+export type JavaScriptExpressionShapeResolver = ReturnType<
+  typeof createSemanticExpressionShapeResolver
+>;
 const commonJsWrapperParameterNames = new Set([
   "exports",
   "require",
@@ -137,3 +142,26 @@ export const createSemanticExpressionShapeResolver = (
     },
   };
 };
+
+/**
+ * Select the options argument of a `(target[, argv][, options])` signature,
+ * such as Node child_process spawn/execFile/fork or Electron
+ * utilityProcess.fork. Only a proven argv array or nullish placeholder admits
+ * third-slot options; any other second argument may itself be the options
+ * object, which makes the runtime ignore the third. Spread arguments are
+ * returned unchanged so callers keep their unknown positions unknown. The
+ * returned node is unwrapped; `undefined` means no options were supplied.
+ */
+export const optionsAfterOptionalArgv = (
+  args: readonly t.CallExpression["arguments"][number][],
+  shapes: JavaScriptExpressionShapeResolver,
+): t.Node | undefined => {
+  const [first, second, third] = args;
+  if (t.isSpreadElement(first)) return first;
+  if (second === undefined) return undefined;
+  const options =
+    shapes.isArray(second) || shapes.isNullish(second) ? third : second;
+  return options === undefined
+    ? undefined
+    : unwrapJavaScriptExpression(options).node;
+};