test(perf): compare saved CLI startup benchmarks (#94812)

Summary:
- Adds saved CLI startup benchmark report comparison flags to `scripts/bench-cli-startup.ts`, plus JSON output coverage and changed-target routing expectations for the new test-helper importer.
- PR surface: Tests +77, Other +109. Total +186 across 4 files.
- Reproducibility: not applicable. as a feature/tooling PR. The prior PR defects were source-proven in review comments and the current head addresses them; I did not run local tests because this review was read-only.

Automerge notes:
- Ran the ClawSweeper repair loop before final review.
- Included post-review commit in the final squash: test(perf): compare saved CLI startup benchmarks

Validation:
- ClawSweeper review passed for head 1afa110f1b.
- Required merge gates passed before the squash merge.

Prepared head SHA: 1afa110f1b
Review: https://github.com/openclaw/openclaw/pull/94812#issuecomment-4748785428

Co-authored-by: clawsweeper <274271284+clawsweeper[bot]@users.noreply.github.com>
Co-authored-by: Felix Isaac Lim <38658663+FelixIsaac@users.noreply.github.com>

test/scripts/test-projects.test.ts

@@ -1918,6 +1918,8 @@ describe("scripts/test-projects changed-target routing", () => {
         "test/helpers/temp-dir.ts": "export const tempDir = 'x';\n",
         "test/helpers/temp-dir.test.ts":
           "import { tempDir } from './temp-dir.js';\nvoid tempDir;\n",
+        "test/scripts/bench-cli-startup.test.ts":
+          "import { tempDir } from '../helpers/temp-dir.js';\nvoid tempDir;\n",
         "src/foo.test.ts":
           "import { tempDir } from '../test/helpers/temp-dir.js';\nvoid tempDir;\n",
       },
@@ -1926,7 +1928,11 @@ describe("scripts/test-projects changed-target routing", () => {
       },
     );
 
-    expect(targets).toEqual(["test/helpers/temp-dir.test.ts", "src/foo.test.ts"]);
+    expect(targets).toEqual([
+      "test/helpers/temp-dir.test.ts",
+      "src/foo.test.ts",
+      "test/scripts/bench-cli-startup.test.ts",
+    ]);
   });
 
   it("keeps the broad changed run available for shared test helpers", () => {