Make DAP Free tier available on self-managed

What does this MR do and why?

Make DAP Free tier available on self-managed

References

Screenshots or screen recordings

	Before	After
Namespace settings
Instance settings	404

How to set up and validate locally

1. Run GDK in SaaS mode GITLAB_SIMULATE_SAAS=0 gdk start
2. Ensure the instance does not have an ultimate license
3. Create a new group (as a sanity check) and within that group create a project
4. In Rails console enable the feature flag and credits

  group = Group.find_by_full_path('your-group-name')
  add_on = GitlabSubscriptions::AddOn.find_or_create_by_name(:gitlab_credits)
  GitlabSubscriptions::AddOnPurchase.create!(
    add_on: add_on,
    namespace: nil,
    organization: group.organization,
    quantity: 1,
    started_at: 1.day.ago,
    expires_on: 1.year.from_now,
    purchase_xid: SecureRandom.hex(16)
  )

5. Within the group settings, GitLab Duo, enable DAP and onboard the Flows
6. Observe that DAP feature are available
7. In your group visit Settings > GitLab Duo > Change Configuration
   1. Enable "Turn on experiment and beta GitLab Duo features" and foundational flows below

Features checklist

Should be available

• Duo agentic chat
• AI Catalog (Explore and Automate, access pages, search)
• Custom Agents (creation, enablement, engagement)
• Custom Flows (creation, enablement, execution) (Requires "Experiment and beta features" in settings to work)
• Foundational Agents (settings, engagement)
• Foundational Agent: Planner
• Foundational Flows (enablement, settings, execution)
• Foundational Flow: Code Review Flow
• Foundational Flow: Convert to GitLab CI/CD Flow
• Foundational Flow: Fix CI/CD Pipeline Flow
• Foundational Flow: Developer Flow
• Foundational Flow: Software Development Flow
• Duo Settings
• Code suggestions

Should not be available

• Classic chat
• Foundational Agent: Security Analyst
• Foundational Flow: SAST Vulnerability Resolution Flow
• Foundational Flow: SAST False Positive Detection Flow
• MCP Server
• Custom Models
• Duo Analytics & SDLC Trends Dashboard
• MCP Client (IDE)

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.