Populate Foundational Flows in AI catalog

Summary

Foundational flows need to be automatically populated in the AI Catalog for self-managed and Dedicated instances, rather than requiring manual creation via gitlab.com.

Problem

Currently, foundational flows are:

1. Defined in Ruby code (Ai::DuoWorkflows::WorkflowDefinition::ITEMS)
2. Manually created in AI Catalog via gitlab.com UI by GitLab developers
3. Not available to self-managed or Dedicated instances

This approach doesn't scale and creates inconsistency between the Ruby definitions and what's actually available in the catalog.

Proposed Solution

Automatically seed/populate AI Catalog items from the foundational flow definitions in WorkflowDefinition::ITEMS (or similar ruby file)

Automatically add the flows to the catalog the first time foundational Flows are enabled across the instance.

Benefits

• Self-managed and Dedicated instances have foundational flows out of the box
• Single source of truth (Ruby code)
• No manual intervention required
• Consistent experience across all GitLab instances

Relevant Code

• app/models/ai/duo_workflows/workflow_definition.rb (ITEMS definition - source of truth)
• app/services/ai/catalog/item_consumers/create_service.rb (item consumer creation)
• AI Catalog item models and services