Use orbit flow version for developer/v1 when user has orbit enabled

What does this MR do and why?

When a user has the duo_developer_orbit feature flag enabled and has the Orbit master toggle turned on in their preferences, the developer/v1 flow is routed to the 2.0.0-orbit flow version instead of the default 2.0.0.

This allows internal testing of the Orbit-aware developer flow variant (introduced in gitlab-org/modelops/applied-ml/code-suggestions/ai-assist#2246 (closed)) without affecting users who have not opted in.

Key changes

FoundationalFlowStartParamsResolver:

• Updated call to accept an optional user: keyword argument
• In resolve_with_overrides, checks duo_developer_orbit feature flag + Ai::Orbit::Settings.killswitch_on?(user) before the duo_developer_next_unstable check — when both conditions are true, returns developer/v1 with version 2.0.0-orbit

Callers (CreateAndStartWorkflowService, ExecuteWorkflowService, DuoWorkflowHelpers):

• Each caller now passes user: current_user to FoundationalFlowStartParamsResolver.call

Behavior matrix

Flow	Condition	DEFINITION	CONFIG_ID	SCHEMA_VERSION	FLOW_VERSION
developer/v1	default (no flags)	developer/v1	developer	v1	2.0.0
developer/v1	duo_developer_orbit on + orbit master toggle on	developer/v1	developer	v1	2.0.0-orbit
developer/v1	duo_developer_next_unstable on	developer_unstable/experimental	developer_unstable	experimental	1.0.0
developer/v1	both duo_developer_orbit (+ toggle) and duo_developer_next_unstable	developer/v1	developer	v1	2.0.0-orbit

Gating logic

• duo_developer_orbit feature flag is the top-level gate — when disabled (default), behavior is unchanged
• Ai::Orbit::Settings.killswitch_on?(user) checks the Orbit master toggle in user preferences as a safety net
• duo_developer_orbit takes priority over duo_developer_next_unstable, so users can explicitly opt into the orbit flow even when the unstable flag is globally enabled

References

• Closes: #599229 (closed)
• Feature flag rollout: #599968
• Related: gitlab-org/modelops/applied-ml/code-suggestions/ai-assist#2246 (closed)

Screenshots or screen recordings

Before	After
N/A (backend only)	N/A (backend only)

How to set up and validate locally

1. Spin up your GDK on latest master

2. Enable the feature flag for a user:

   user = User.find_by_username('your-username')
   Feature.enable(:duo_developer_orbit, user)

3. Enable the Orbit master toggle in user preferences:

   user.user_preference.update!(orbit_settings: { 'enabled' => true })

4. Trigger the Duo Developer flow

5. Check the CI job variables — DUO_WORKFLOW_FLOW_VERSION should be 2.0.0-orbit

MR acceptance checklist

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