fix(anthropic-effort): skip effort injection for github-copilot provider (#3270)

github-copilot routes Claude models but rejects the Anthropic effort
parameter. Added an explicit guard so effort is no longer injected
when the provider ID is github-copilot, while preserving native
Anthropic provider support.

🤖 Generated with OhMyOpenCode assistance
https://github.com/code-yeongyu/oh-my-opencode

src/hooks/anthropic-effort/hook.ts

@@ -65,6 +65,7 @@ export function createAnthropicEffortHook() {
       if (isEffortUnsupportedModel(model.modelID)) return
       if (message.variant !== "max") return
       if (!isClaudeProvider(model.providerID, model.modelID)) return
+      if (model.providerID === "github-copilot") return
       if (shouldSkipForInternalAgent(agent?.name)) return
       if (output.options.effort !== undefined) return