ci: enable Grok qualification in the trusted paid workflow (#13845)

## Thinking Path

> - Paperclip manages AI agents and their work.
> - Product E2E tests verify tasks through the browser, server, and
runner.
> - These paid tests use a trusted workflow from master and an isolated
target commit.
> - The Grok target branch selects XAI_API_KEY, but the trusted workflow
does not deliver that credential.
> - Its artifact test also needs the pinned Python verifier before
execution.
> - This pull request adds both bindings inside the existing paid
boundary.
> - The tests can then run on the configured EC2 fleet without laptop
Docker.

## Linked Issues or Issue Description

Related evaluation infrastructure:
https://github.com/paperclipai/paperclip/pull/11297. No duplicate Grok
paid-workflow change was found.

**What existing behavior does this improve?**

Branch-targeted Grok Product E2E qualification in the existing paid
workflow.

**Current behavior**

Grok cells cannot receive their selected API credential. The Grok
build-revise case also misses the artifact-verifier setup step.

**Proposed behavior**

Deliver XAI_API_KEY only when the selected matrix credential is
XAI_API_KEY. Prepare the existing pinned verifier for the Grok
qualification suite.

**Reason and benefit**

Run the controller, browser, runner and artifact checks on the EC2
fleet. Preserve default-branch workflow authorization and protected
environment secret access.

## What Changed

- Bind the selected XAI credential only in the paid test step.
- Install the checksum-verified Grok binary for local cells before
provider access.
- Include Grok qualification in the existing pinned artifact-verifier
preparation.
- Add an optional max_parallel input that can only lower the configured
campaign concurrency. Use 1 for the Grok test key.
- Extend security assertions and document setup.

## Verification

- Ran the Product E2E workflow-security tests: 11 passed.
- Checked the diff for whitespace errors.
- Reviewed credential selection, setup ordering, numeric actor gates,
target commit pinning, and trusted report checkout.
- Live Grok execution follows after this workflow is available on
master. This PR does not claim completed Grok qualification.

## Risks

The paid test step can use the selected XAI credential and incur
provider charges. The credential remains in runner-e2e-paid and is
absent from setup, build, and reporting jobs. The default-branch gate
and existing environment restrictions remain in place. No database
migration or product behavior changes.

## Model Used

OpenAI Codex, GPT-6 family, with reasoning, code editing, and tool
execution. The exact deployment model ID and context-window size are not
exposed in this session.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [ ] All Paperclip CI gates are green
- [ ] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

tests/runner-e2e/workflow-security.test.ts

@@ -294,12 +294,18 @@ describe("public repository paid workflow security", () => {
     expect(paidExecution).toBeGreaterThan(awsFfmpegInstall);
     expect(paidExecution).toBeGreaterThan(daytonaPluginPreparation);
     expect(paidExecution).toBeGreaterThan(everydayOraclePreparation);
+    const grokPreparation = paidJob.indexOf("- name: Install checksum-verified Grok executable");
+    expect(grokPreparation).toBeGreaterThan(paidInstall);
+    expect(paidExecution).toBeGreaterThan(grokPreparation);
+    expect(paidJob).toContain("if: matrix.environmentId == 'local' && matrix.profileId == 'runner-acpx-grok'");
+    expect(paidJob).toContain("run: node packages/grok-acp/install.mjs");
+
     const everydayOracleStep = paidJob.slice(
       everydayOraclePreparation,
       paidExecution,
     );
     expect(everydayOracleStep).toContain(
-      "if: matrix.suiteId == 'everyday-workflows' && (matrix.caseId == 'build-revise' || matrix.caseId == 'delegate-feedback' || matrix.caseId == 'agent-review-handoff' || matrix.caseId == 'hire-reuse' || matrix.caseId == 'recover-controller' || matrix.caseId == 'stop-redirect')",
+      "if: (matrix.suiteId == 'everyday-workflows' || matrix.suiteId == 'grok-qualification') && (matrix.caseId == 'build-revise' || matrix.caseId == 'delegate-feedback' || matrix.caseId == 'agent-review-handoff' || matrix.caseId == 'hire-reuse' || matrix.caseId == 'recover-controller' || matrix.caseId == 'stop-redirect')",
     );
     expect(everydayOracleStep).toContain(
       `oracle_image='${everydayOracleImage}'`,
@@ -367,6 +373,10 @@ describe("public repository paid workflow security", () => {
     );
     expect(authorizeJob).toContain('echo "max_parallel_limit=100"');
     expect(fullStack).toContain('[ "$MAX_PARALLEL_LIMIT" -gt 100 ]');
+    expect(fullStack).toContain("REQUESTED_MAX_PARALLEL: ${{ inputs.max_parallel }}");
+    expect(fullStack).toContain('[ "$REQUESTED_MAX_PARALLEL" -gt "$MAX_PARALLEL" ]');
+    expect(fullStack).toContain('[[ "$REQUESTED_MAX_PARALLEL" =~ ^[1-9][0-9]{0,2}$ ]]');
+
     expect(fullStack).toContain(
       '[ "$MAX_PARALLEL" -gt "$MAX_PARALLEL_LIMIT" ]',
     );
@@ -511,6 +521,7 @@ describe("public repository paid workflow security", () => {
       OPENAI_API_KEY: "matrix.credentialName == 'OPENAI_API_KEY'",
       ANTHROPIC_API_KEY: "matrix.credentialName == 'ANTHROPIC_API_KEY'",
       OPENROUTER_API_KEY: "matrix.credentialName == 'OPENROUTER_API_KEY'",
+      XAI_API_KEY: "matrix.credentialName == 'XAI_API_KEY'",
       DAYTONA_API_KEY: "matrix.environmentId == 'daytona'",
     })) {
       expect(fullStack).toContain(
@@ -538,7 +549,7 @@ describe("public repository paid workflow security", () => {
       );
       const providerSecretReferences = [
         ...contents.matchAll(
-          /secrets(?:\.(?:OPENAI_API_KEY|ANTHROPIC_API_KEY|OPENROUTER_API_KEY|DAYTONA_API_KEY)\b|\[['"](?:OPENAI_API_KEY|ANTHROPIC_API_KEY|OPENROUTER_API_KEY|DAYTONA_API_KEY)['"]\])/g,
+          /secrets(?:\.(?:OPENAI_API_KEY|ANTHROPIC_API_KEY|OPENROUTER_API_KEY|XAI_API_KEY|DAYTONA_API_KEY)\b|\[['"](?:OPENAI_API_KEY|ANTHROPIC_API_KEY|OPENROUTER_API_KEY|XAI_API_KEY|DAYTONA_API_KEY)['"]\])/g,
         ),
       ];
       if (providerSecretReferences.length > 0) {