Remove GitHub Copilot provider support

Remove all GitHub Copilot integration from the codebase to streamline
the supported provider set to OpenAI, OpenRouter, Anthropic, and Ollama.

Changes:
- Delete core Copilot implementation (copilot.go) and all related tests
- Remove Copilot configuration fields from App struct and Config
- Remove Copilot from provider factory and API key handling
- Update all test files to replace Copilot references with other providers
- Remove Copilot documentation from README, configuration guide, and examples
- Remove Copilot section from config.toml.example

All tests pass successfully after removal.

Co-authored-by: Cursor <cursoragent@cursor.com>

3 files changed, 12 insertions, 17 deletions

diff --git a/internal/hexaicli/run.go b/internal/hexaicli/run.go
index 7b360e9..9ea3a40 100644
--- a/internal/hexaicli/run.go
+++ b/internal/hexaicli/run.go
@@ -77,10 +77,6 @@ func buildCLIJobs(cfg appconfig.App) ([]cliJob, error) {
 			if entry.Model != "" {
 				derived.OpenAIModel = entry.Model
 			}
-		case "copilot":
-			if entry.Model != "" {
-				derived.CopilotModel = entry.Model
-			}
 		case "ollama":
 			if entry.Model != "" {
 				derived.OllamaModel = entry.Model
@@ -151,8 +147,8 @@ func defaultModelForProvider(cfg appconfig.App, provider string) string {
 	switch provider {
 	case "ollama":
 		return cfg.OllamaModel
-	case "copilot":
-		return cfg.CopilotModel
+	case "anthropic":
+		return cfg.AnthropicModel
 	default:
 		return cfg.OpenAIModel
 	}
diff --git a/internal/hexaicli/run_test.go b/internal/hexaicli/run_test.go
index 43576cf..34a5c51 100644
--- a/internal/hexaicli/run_test.go
+++ b/internal/hexaicli/run_test.go
@@ -161,11 +161,11 @@ func TestPrintProviderInfo(t *testing.T) {
 
 func TestBuildCLIRequest_Override(t *testing.T) {
 	cfg := appconfig.App{
-		Provider:     "openai",
-		CopilotModel: "gpt-4o",
+		Provider:       "openai",
+		AnthropicModel: "claude-3-5-sonnet",
 	}
-	entry := appconfig.SurfaceConfig{Provider: "copilot", Model: "override", Temperature: floatPtr(0.7)}
-	req := buildCLIRequest(entry, "copilot", cfg, &fakeClient{name: "copilot", model: "default"})
+	entry := appconfig.SurfaceConfig{Provider: "anthropic", Model: "override", Temperature: floatPtr(0.7)}
+	req := buildCLIRequest(entry, "anthropic", cfg, &fakeClient{name: "anthropic", model: "default"})
 	if req.model != "override" {
 		t.Fatalf("expected model override, got %q", req.model)
 	}
@@ -199,8 +199,8 @@ func TestBuildCLIJobs_MultiEntries(t *testing.T) {
 	defer func() { newClientFromApp = old }()
 	newClientFromApp = func(cfg appconfig.App) (llm.Client, error) {
 		model := cfg.OpenAIModel
-		if cfg.Provider == "copilot" {
-			model = cfg.CopilotModel
+		if cfg.Provider == "anthropic" {
+			model = cfg.AnthropicModel
 		}
 		if cfg.Provider == "ollama" {
 			model = cfg.OllamaModel
@@ -215,7 +215,7 @@ func TestBuildCLIJobs_MultiEntries(t *testing.T) {
 		OllamaModel: "llama3",
 		CLIConfigs: []appconfig.SurfaceConfig{
 			{Provider: "openai", Model: "gpt-4o"},
-			{Provider: "copilot", Model: "cpt"},
+			{Provider: "anthropic", Model: "claude"},
 		},
 	}
 	jobs, err := buildCLIJobs(cfg)
@@ -228,18 +228,18 @@ func TestBuildCLIJobs_MultiEntries(t *testing.T) {
 	if jobs[0].provider != "openai" || jobs[0].req.model != "gpt-4o" {
 		t.Fatalf("unexpected first job: %+v", jobs[0])
 	}
-	if jobs[1].provider != "copilot" || jobs[1].req.model != "cpt" {
+	if jobs[1].provider != "anthropic" || jobs[1].req.model != "claude" {
 		t.Fatalf("unexpected second job: %+v", jobs[1])
 	}
 }
 
 func TestFilterJobsBySelection(t *testing.T) {
-	jobs := []cliJob{{index: 0, provider: "openai"}, {index: 1, provider: "ollama"}, {index: 2, provider: "copilot"}}
+	jobs := []cliJob{{index: 0, provider: "openai"}, {index: 1, provider: "ollama"}, {index: 2, provider: "anthropic"}}
 	filtered, err := filterJobsBySelection(jobs, []int{2, 0})
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if len(filtered) != 2 || filtered[0].provider != "copilot" || filtered[1].provider != "openai" {
+	if len(filtered) != 2 || filtered[0].provider != "anthropic" || filtered[1].provider != "openai" {
 		t.Fatalf("unexpected filtered order: %+v", filtered)
 	}
 	if filtered[0].index != 0 || filtered[1].index != 1 {
diff --git a/internal/hexaicli/testhelpers_test.go b/internal/hexaicli/testhelpers_test.go
index 8f6863d..3197880 100644
--- a/internal/hexaicli/testhelpers_test.go
+++ b/internal/hexaicli/testhelpers_test.go
@@ -63,7 +63,6 @@ func (s *fakeStreamer) ChatStream(ctx context.Context, messages []llm.Message, o
 	return nil
 }
 
-
 func writeConfigString(t *testing.T, path string, contents string) {
 	t.Helper()
 	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {