feat: add GPT-4o to GitHub Copilot provider

[I3eka]

Summary

Added GPT-4o to the list of supported models for the GitHub Copilot (gh) provider.

Changes

• Updated PROVIDER_MODELS constant.
• Added { id: "gpt-4o", name: "GPT-4o" } to the gh array.

Motivation

Enables users to select GPT-4o when using the GitHub Copilot provider key.

[Copilot]

Pull request overview

Adds gpt-4o as a selectable model for the GitHub Copilot (gh) provider by updating the central provider→models mapping.

Changes:

• Added { id: "gpt-4o", name: "GPT-4o" } to the gh provider’s model list.
• Updated the PROVIDER_MODELS configuration to include the new model ID/name pair.

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[Copilot]

Adding gpt-4o as the first entry changes the implicit default for the gh provider (since getDefaultModel() returns models?.[0]?.id). If the intent is only to make GPT-4o selectable (not the default/recommended), place it later in the list or add an explicit default-selection mechanism elsewhere so this ordering change doesn’t affect behavior/UI ordering unintentionally.

Suggested change

	{ id: "gpt-4o", name: "GPT-4o"},
	{ id: "gpt-4.1", name: "GPT-4.1" },
	{ id: "gpt-4.1", name: "GPT-4.1" },
	{ id: "gpt-4o", name: "GPT-4o"},