Fixed: #2034

feat(proxy): centralize proxy handling with `proxyutil` package and enhance test coverage

- Added `proxyutil` package to simplify proxy handling across the codebase.
- Refactored various components (`executor`, `cliproxy`, `auth`, etc.) to use `proxyutil` for consistent and reusable proxy logic.
- Introduced support for "direct" proxy mode to explicitly bypass all proxies.
- Updated tests to validate proxy behavior (e.g., `direct`, HTTP/HTTPS, and SOCKS5).
- Enhanced YAML configuration documentation for proxy options.

sdk/proxyutil/proxy_test.go

@@ -0,0 +1,89 @@
+package proxyutil
+
+import (
+	"net/http"
+	"testing"
+)
+
+func TestParse(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		input   string
+		want    Mode
+		wantErr bool
+	}{
+		{name: "inherit", input: "", want: ModeInherit},
+		{name: "direct", input: "direct", want: ModeDirect},
+		{name: "none", input: "none", want: ModeDirect},
+		{name: "http", input: "http://proxy.example.com:8080", want: ModeProxy},
+		{name: "https", input: "https://proxy.example.com:8443", want: ModeProxy},
+		{name: "socks5", input: "socks5://proxy.example.com:1080", want: ModeProxy},
+		{name: "invalid", input: "bad-value", want: ModeInvalid, wantErr: true},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			setting, errParse := Parse(tt.input)
+			if tt.wantErr && errParse == nil {
+				t.Fatal("expected error, got nil")
+			}
+			if !tt.wantErr && errParse != nil {
+				t.Fatalf("unexpected error: %v", errParse)
+			}
+			if setting.Mode != tt.want {
+				t.Fatalf("mode = %d, want %d", setting.Mode, tt.want)
+			}
+		})
+	}
+}
+
+func TestBuildHTTPTransportDirectBypassesProxy(t *testing.T) {
+	t.Parallel()
+
+	transport, mode, errBuild := BuildHTTPTransport("direct")
+	if errBuild != nil {
+		t.Fatalf("BuildHTTPTransport returned error: %v", errBuild)
+	}
+	if mode != ModeDirect {
+		t.Fatalf("mode = %d, want %d", mode, ModeDirect)
+	}
+	if transport == nil {
+		t.Fatal("expected transport, got nil")
+	}
+	if transport.Proxy != nil {
+		t.Fatal("expected direct transport to disable proxy function")
+	}
+}
+
+func TestBuildHTTPTransportHTTPProxy(t *testing.T) {
+	t.Parallel()
+
+	transport, mode, errBuild := BuildHTTPTransport("http://proxy.example.com:8080")
+	if errBuild != nil {
+		t.Fatalf("BuildHTTPTransport returned error: %v", errBuild)
+	}
+	if mode != ModeProxy {
+		t.Fatalf("mode = %d, want %d", mode, ModeProxy)
+	}
+	if transport == nil {
+		t.Fatal("expected transport, got nil")
+	}
+
+	req, errRequest := http.NewRequest(http.MethodGet, "https://example.com", nil)
+	if errRequest != nil {
+		t.Fatalf("http.NewRequest returned error: %v", errRequest)
+	}
+
+	proxyURL, errProxy := transport.Proxy(req)
+	if errProxy != nil {
+		t.Fatalf("transport.Proxy returned error: %v", errProxy)
+	}
+	if proxyURL == nil || proxyURL.String() != "http://proxy.example.com:8080" {
+		t.Fatalf("proxy URL = %v, want http://proxy.example.com:8080", proxyURL)
+	}
+}