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>

.github/workflows/runner-full-stack-e2e.yml

@@ -9,6 +9,10 @@ on:
         description: "Branch in paperclipai/paperclip to test; the trusted workflow still runs from master"
         type: string
         required: false
+      max_parallel:
+        description: "Optional lower concurrency for this campaign (cannot exceed the configured limit)"
+        type: string
+        required: false
       all:
         description: "Run the complete paid matrix when no narrower selector is supplied"
         type: boolean
@@ -286,6 +290,7 @@ jobs:
           SELECT_ID: ${{ inputs.id }}
           MAX_PARALLEL: ${{ vars.RUNNER_E2E_MAX_PARALLEL || needs.authorize.outputs.max_parallel_default }}
           MAX_PARALLEL_LIMIT: ${{ needs.authorize.outputs.max_parallel_limit }}
+          REQUESTED_MAX_PARALLEL: ${{ inputs.max_parallel }}
         run: |
           set -euo pipefail
           args=(--matrix-json)
@@ -346,6 +351,13 @@ jobs:
             echo "RUNNER_E2E_MAX_PARALLEL must be an integer from 1 through $MAX_PARALLEL_LIMIT for the selected runner." >&2
             exit 1
           fi
+          if [ -n "${REQUESTED_MAX_PARALLEL:-}" ]; then
+            if ! [[ "$REQUESTED_MAX_PARALLEL" =~ ^[1-9][0-9]{0,2}$ ]] || [ "$REQUESTED_MAX_PARALLEL" -gt "$MAX_PARALLEL" ]; then
+              echo "max_parallel must be an integer from 1 through the configured campaign limit." >&2
+              exit 1
+            fi
+            MAX_PARALLEL="$REQUESTED_MAX_PARALLEL"
+          fi
           echo "max_parallel=$MAX_PARALLEL" >> "$GITHUB_OUTPUT"
 
   daytona_image:
@@ -874,6 +886,10 @@ jobs:
         if: matrix.environmentId == 'local' && (matrix.profileId == 'legacy-opencode' || matrix.profileId == 'runner-opencode' || matrix.suiteId == 'openrouter-model-breadth')
         run: node packages/paperclip-runner/scripts/materialize-opencode-binary.mjs
 
+      - name: Install checksum-verified Grok executable
+        if: matrix.environmentId == 'local' && matrix.profileId == 'runner-acpx-grok'
+        run: node packages/grok-acp/install.mjs
+
       - name: Download immutable campaign outputs
         if: startsWith(matrix.profileId, 'runner-') || matrix.suiteId == 'openrouter-model-breadth'
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
@@ -1024,7 +1040,7 @@ jobs:
           NODE
 
       - name: Prepare pinned Python artifact oracle image
-        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')
         run: |
           set -euo pipefail
           oracle_image='python@sha256:9d2e5553305c7c7b0097999bb17187c69b921ccd6bc9d40e4bb5ebe652c00285'
@@ -1037,6 +1053,7 @@ jobs:
           OPENAI_API_KEY: ${{ matrix.credentialName == 'OPENAI_API_KEY' && secrets.OPENAI_API_KEY || '' }}
           ANTHROPIC_API_KEY: ${{ matrix.credentialName == 'ANTHROPIC_API_KEY' && secrets.ANTHROPIC_API_KEY || '' }}
           OPENROUTER_API_KEY: ${{ matrix.credentialName == 'OPENROUTER_API_KEY' && secrets.OPENROUTER_API_KEY || '' }}
+          XAI_API_KEY: ${{ matrix.credentialName == 'XAI_API_KEY' && secrets.XAI_API_KEY || '' }}
           DAYTONA_API_KEY: ${{ matrix.environmentId == 'daytona' && secrets.DAYTONA_API_KEY || '' }}
           PAPERCLIP_E2E_DAYTONA_IMAGE: ${{ needs.daytona_image.outputs.image }}
           PAPERCLIP_RUNNER_REMOTE_PROVIDER_PACK_PATH: ${{ github.workspace }}/packages/paperclip-runner/provider-pack