add 21-4138 to dashboard and add tests

[dominicpadula1]

• This work is behind a feature toggle (flipper): NO Turned off in prod
• Adds VA Form 21-4138 (Statement in Support of Claim) to the My VA form submission statuses dashboard. Veterans who have submitted this form can now track its status alongside other supported benefits intake forms.
• This is a one-line addition to the restricted_benefits_intake_forms allowlist in SubmissionStatusesController. No new logic was introduced — 21-4138 is handled by the existing Benefits Intake gateway, formatter, and report pipeline.
• This work is owned by the design system and forms team.

Related issue(s)

• Form 21-4138: Add form to My VA status vets-design-system-documentation#6059

Testing done

• New code is covered by unit tests
• Before: 21-4138 submissions were not included in the restricted_benefits_intake_forms allowlist, so they were filtered out and never surfaced on the My VA dashboard.
• After: 21-4138 is included in the allowlist. The gateway picks up matching FormSubmission records, fetches their status from the Lighthouse Benefits Intake bulk status API, and returns them to the frontend.
• Tests added in:
  • spec/controllers/v0/my_va/submission_statuses_controller_spec.rb — verifies 21-4138 is present in restricted_benefits_intake_forms
    and is passed as an allowed form to the report when the feature flag is disabled
  • spec/lib/forms/submission_statuses/report_spec.rb — verifies 21-4138 submissions are included in report results with correct field
    values
  • spec/factories/form_submissions.rb — added with_form214138 factory trait

Screenshots

N/A

What areas of the site does it impact?

Impacts the My VA dashboard submission statuses endpoint (GET /v0/my_va/submission_statuses). No other areas are affected.

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No error nor warning in the console.
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs

[Copilot]

Pull request overview

Adds VA Form 21-4138 (Statement in Support of Claim) to the My VA submission statuses dashboard by extending the restricted Benefits Intake allowlist, with supporting specs/factory coverage so 21-4138 submissions appear alongside other tracked forms.

Changes:

• Added 21-4138 to the restricted_benefits_intake_forms allowlist used by GET /v0/my_va/submission_statuses.
• Added controller spec coverage asserting 21-4138 is included in the restricted list.
• Added report spec + factory trait coverage to ensure 21-4138 FormSubmission records are included and formatted as expected.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
app/controllers/v0/my_va/submission_statuses_controller.rb	Adds 21-4138 to the restricted Benefits Intake forms allowlist used when returning submission statuses.
spec/controllers/v0/my_va/submission_statuses_controller_spec.rb	Updates restricted-list spec to assert 21-4138 is present.
spec/lib/forms/submission_statuses/report_spec.rb	Expands report spec allowed forms and adds a 21-4138-specific report inclusion/value check.
spec/factories/form_submissions.rb	Adds a factory trait to create FormSubmission records for 21-4138 with a known Benefits Intake UUID.