feat: add .air.toml configuration file and update .gitignore for build artifacts

fix: improve PatchOAuthModelAlias logic for handling channel aliases

feat: add support for GitHub Copilot in model definitions

internal/registry/model_definitions.go

@@ -19,6 +19,7 @@ import (
 //   - codex
 //   - qwen
 //   - iflow
+//   - github-copilot
 //   - antigravity (returns static overrides only)
 func GetStaticModelDefinitionsByChannel(channel string) []*ModelInfo {
 	key := strings.ToLower(strings.TrimSpace(channel))
@@ -39,6 +40,8 @@ func GetStaticModelDefinitionsByChannel(channel string) []*ModelInfo {
 		return GetQwenModels()
 	case "iflow":
 		return GetIFlowModels()
+	case "github-copilot":
+		return GetGitHubCopilotModels()
 	case "antigravity":
 		cfg := GetAntigravityModelConfig()
 		if len(cfg) == 0 {