Wire Developer activity and Project exposure cards to real backend data

Note: Dependent on the MR

• Add top user and project session rankings to AI... (!250274 - merged) • Andrew Jung • 19.4

What

Swaps the mocked Developer activity and Project exposure dashboard cards to real data from aiGovernanceMetrics.topUsers / topProjects.

Why

Follow-up to !250049 (merged) (which shipped these cards with mock data behind the ai_governance_dashboard flag). Closes #611950 and #611951.

Note on the backend commits

This branch cherry-picks 3 backend commits so it is self-contained and reviewable end to end:

• Include Duo Chat in sessions KPI (from !248831 (merged))
• Add top user/project session rankings (from !250274 (merged))
• Preload project routes in rankings When those backend MRs merge to master, a rebase drops these commits, leaving only the frontend swap.

Tests

Updated developer_activity_card_spec and project_exposure_card_spec to use real Apollo mocks.

Verification (local GDK)

Rendered on this stacked branch (backend rankings + this FE) against seeded ranked sessions on the gitlab-duo group. Both cards pull live from aiGovernanceMetrics.topUsers / topProjects.

Developer activity

Project exposure

Full dashboard