fix(e2e): preserve host command execution boundary (#10439)

## Summary

Keeps the host PATH when ShellProbe merges an explicit command
environment, without inheriting ambient workflow secrets. Also keeps the
fixture shell-quoting helper self-contained so the independent tsx
cleanup controller does not cross the CommonJS source compiler boundary.

## Related Issue

Refs #9880

## Verification

- Focused E2E support tests: 93 passed
- Independent cleanup controller loads and exits successfully without an
ownership receipt
- CLI build and TypeScript passed
- Commit and push hooks passed

Signed-off-by: Julie Yaunches <jyaunches@nvidia.com>

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Bug Fixes**
- Improved shell-based workload execution by preserving the host `PATH`
while still applying command-specific environment overrides.
- Enhanced handling of shell-quoted values, including inputs containing
apostrophes.

- **Tests**
- Added end-to-end coverage confirming commands can be resolved through
the preserved `PATH` and receive custom environment variables correctly.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Julie Yaunches <jyaunches@nvidia.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: jyaunches

test/e2e/fixtures/clients/command.ts

@@ -7,7 +7,9 @@ import type {
   TrustedShellCommand,
 } from "../shell-probe.ts";
 
-export { shellQuote } from "../../../../src/lib/core/shell-quote.ts";
+export function shellQuote(value: unknown): string {
+  return `'${String(value).replace(/'/g, `'\\''`)}'`;
+}
 
 export interface CommandRunner {
   run(command: TrustedShellCommand, options?: ShellProbeRunOptions): Promise<ShellProbeResult>;

test/e2e/support/e2e-fixture-context.test.ts

@@ -331,6 +331,30 @@ describe("E2E fixture primitives", () => {
     }
   });
 
+  it("shell probe inherits the host PATH when command options add environment variables", async () => {
+    const tmp = fs.mkdtempSync(path.join(os.tmpdir(), "nemoclaw-e2e-shell-probe-path-"));
+    try {
+      const probe = new ShellProbe({
+        artifacts: new ArtifactSink(tmp),
+        progress: supportProgress(),
+        redact: (text) => text,
+        signal: new AbortController().signal,
+      });
+      const result = await probe.run(
+        trustedShellCommand({
+          command: "node",
+          args: ["-e", "process.stdout.write(process.env.PROBE_VALUE ?? '')"],
+          reason: "verify ShellProbe keeps PATH while merging command environment",
+        }),
+        { env: { PROBE_VALUE: "present" }, timeoutMs: 5_000 },
+      );
+      expect(result.exitCode).toBe(0);
+      expect(result.stdout).toBe("present");
+    } finally {
+      fs.rmSync(tmp, { recursive: true, force: true });
+    }
+  });
+
   it("shell probe reports child liveness to the shared observer without duplicating it", async () => {
     const tmp = fs.mkdtempSync(path.join(os.tmpdir(), "nemoclaw-e2e-shell-observer-"));
     try {