perf(tests): reuse MCP connections within source matrices

Reuse test-owned stdio MCP connections within two stateless source-analysis matrices while retaining every original CLI/MCP scenario, schema/Evidence checks and test-finished cleanup. Add cross-input identity controls.

Validation: 23 focused public-workflow tests and complete check:ci passed; stale-response fault detected. Exact-head hosted CI and available review passed. Pinned workload measurements and their limits are recorded in the PR.

Refs #4737.

tests/support/cli/javascriptApplication.ts

@@ -21,11 +21,12 @@ export const runNodeJsonControl = async (
   return JSON.parse(stdout) as unknown;
 };
 
-/** Analyze a directory through a public adapter and validate its result contract. */
+/** Analyze a directory; a supplied MCP caller reuses its test-owned connection. */
 export const analyzeJavaScriptDirectory = async (
   surface: "CLI" | "stdio MCP",
   cli: TestCli,
   root: string,
+  mcpCall?: Awaited<ReturnType<typeof connectLocalToolsMcp>>["call"],
 ) => {
   let document: unknown;
   if (surface === "CLI") {
@@ -36,7 +37,7 @@ export const analyzeJavaScriptDirectory = async (
     expect(response.exitCode, response.stderr).toBe(0);
     document = response.json;
   } else {
-    const { call } = await connectLocalToolsMcp();
+    const call = mcpCall ?? (await connectLocalToolsMcp()).call;
     const response = await call("analyze_javascript_application", {
       input_path: root,
       format: "directory",