show active AI provider at the top of the providers list

[atomantic]

Summary

• On the AI Providers settings page, the provider marked DEFAULT (the active provider) now renders first in the list. Other providers keep their existing order beneath it.
• Implementation is a partition + spread in the render path — no state or sort key changes.

Test plan

• Visit Settings → AI Providers with multiple providers configured.
• Confirm the provider tagged DEFAULT appears at the top of the list.
• Click "Set Default" on a different provider; confirm the list re-orders so the newly-active one moves to the top without a refresh.
• With no active provider set (activeProviderId null), confirm the list renders in the original order without crashing.

[Copilot]

Pull request overview

Reorders the AI Providers settings list so the currently active provider (tagged DEFAULT) appears first, while preserving the existing relative order of all other providers.

Changes:

• Adjusted the provider list render path to move the active provider to the top of the displayed list.
• Kept ordering logic local to rendering (no persisted sort key/state changes).

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.