Harden GitHub Actions: fix injections, isolate privileged operations to ci-privileged repo (#18318)

## Summary

- Fix expression injection vulnerabilities in composite actions
(`restore-cache`, `nx-affected`) and workflow files (`claude.yml`)
- Reduce overly broad permissions in `ci-utils.yaml` (Danger.js) and
`ci-breaking-changes.yaml`
- Restructure `preview-env-dispatch.yaml`: auto-trigger for members,
opt-in for contributor PRs via `preview-app` label (safe because
keepalive has no write tokens)
- Isolate all write-access operations (PR comments, cross-repo posting)
to a new dedicated
[`twentyhq/ci-privileged`](https://github.com/twentyhq/ci-privileged)
repo via `repository_dispatch`, so that workflows in twenty that execute
contributor code never have write tokens
- Create `post-ci-comments.yaml` (`workflow_run` bridge) to dispatch
breaking changes results to ci-privileged, solving the [fork PR comment
issue](https://github.com/twentyhq/twenty/pull/13713#issuecomment-3168999083)
- Delete 5 unused secrets and broken `i18n-qa-report` workflow
- Remove `TWENTY_DISPATCH_TOKEN` from twenty (moved to ci-privileged as
`CORE_TEAM_ISSUES_COMMENT_TOKEN`)
- Use `toJSON()` for all `client-payload` values to prevent JSON
injection

## Security model after this PR

| Workflow | Executes fork code? | Write tokens available? |
|----------|---------------------|------------------------|
| preview-env-keepalive | Yes | None (contents: read only) |
| preview-env-dispatch | No (base branch) | CI_PRIVILEGED_DISPATCH_TOKEN
only |
| ci-breaking-changes | Yes | None (contents: read only) |
| post-ci-comments (workflow_run) | No (default branch) |
CI_PRIVILEGED_DISPATCH_TOKEN only |
| claude.yml | No (base branch) | CI_PRIVILEGED_DISPATCH_TOKEN,
CLAUDE_CODE_OAUTH_TOKEN |
| ci-utils (Danger.js) | No (base branch) | GITHUB_TOKEN (scoped) |

All actual write tokens (`TWENTY_PR_COMMENT_TOKEN`,
`CORE_TEAM_ISSUES_COMMENT_TOKEN`) live in `twentyhq/ci-privileged` with
strict CODEOWNERS review and branch protection.

## Test plan

- [ ] Verify preview environment comments still appear on member PRs
- [ ] Verify adding `preview-app` label triggers preview for contributor
PRs
- [ ] Verify breaking changes reports still post on PRs (including fork
PRs)
- [ ] Verify Claude cross-repo responses still post on core-team-issues
- [ ] Confirm ci-privileged branch protection is enforced

.github/actions/nx-affected/action.yaml

@@ -19,4 +19,10 @@ runs:
       uses: nrwl/nx-set-shas@v4
     - name: Run affected command
       shell: bash
-      run: npx nx affected --nxBail --configuration=${{ inputs.configuration }} -t=${{ inputs.tasks }} --parallel=${{ inputs.parallel }} --exclude='*,!tag:${{ inputs.tag }}' ${{ inputs.args }}
+      env:
+        NX_CONFIGURATION: ${{ inputs.configuration }}
+        NX_TASKS: ${{ inputs.tasks }}
+        NX_PARALLEL: ${{ inputs.parallel }}
+        NX_TAG: ${{ inputs.tag }}
+        NX_ARGS: ${{ inputs.args }}
+      run: npx nx affected --nxBail --configuration="$NX_CONFIGURATION" -t="$NX_TASKS" --parallel="$NX_PARALLEL" --exclude="*,!tag:$NX_TAG" $NX_ARGS

.github/actions/restore-cache/action.yaml

@@ -19,8 +19,11 @@ runs:
     - name: Cache primary key builder
       id: cache-primary-key-builder
       shell: bash
+      env:
+        CACHE_KEY: ${{ inputs.key }}
+        REF_NAME: ${{ github.ref_name }}
       run: |
-        echo "CACHE_PRIMARY_KEY_PREFIX=v4-${{ inputs.key }}-${{ github.ref_name }}" >> "${GITHUB_OUTPUT}"
+        echo "CACHE_PRIMARY_KEY_PREFIX=v4-${CACHE_KEY}-${REF_NAME}" >> "${GITHUB_OUTPUT}"
     - name: Restore cache
       uses: actions/cache/restore@v4
       id: restore-cache