feat: security hardening, tests, doctor command, CI update, CHANGELOG

- Add AES-256-GCM encryption for API keys (internal/secret)
- Add dangerous command detection in terminal
- Add muyue doctor command for system health checks
- Add scanner TTL cache, orchestrator history mutex, shared HTTP client
- Deduplicate MCP config generation, refactor skills YAML parser
- Add XDG-compliant config dir with legacy migration
- Add cleanup on all TUI quit paths
- Add 8 test files (config, workflow, skills, orchestrator, version,
  platform, scanner, secret)
- Update CI to actions/setup-go@v5
- Add CHANGELOG.md, update README and Makefile

🤖 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

internal/version/version_test.go

@@ -0,0 +1,31 @@
+package version
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestFullVersion(t *testing.T) {
+	v := FullVersion()
+	if !strings.HasPrefix(v, Name) {
+		t.Errorf("FullVersion should start with %s, got %s", Name, v)
+	}
+	if !strings.Contains(v, "v"+Version) {
+		t.Errorf("FullVersion should contain v%s, got %s", Version, v)
+	}
+}
+
+func TestConstants(t *testing.T) {
+	if Name == "" {
+		t.Error("Name should not be empty")
+	}
+	if Version == "" {
+		t.Error("Version should not be empty")
+	}
+	if Author == "" {
+		t.Error("Author should not be empty")
+	}
+	if License == "" {
+		t.Error("License should not be empty")
+	}
+}