feat(07-02): implement PrintConfig function with comment annotations

- Add AutoClasses map[TrafficClass]bool to LoadResult for tracking auto-assigned classes
- PrintConfig() returns commented TOML with header (source, date), [[rules]] section, [sounds.*] section
- waveformString() helper converts WaveformType back to string
- classAnnotation() returns default/override/auto-assigned per class
- Built-in classes emitted in AllClasses() order; user-defined classes sorted alphabetically
- Rules section emits [[rules]] blocks; port omitted when DstPort==0
- Tests: TestPrintConfigContainsAllClasses, TestPrintConfigSourcePath, TestPrintConfigNoSourcePath,
  TestPrintConfigContainsRules, TestPrintConfigRuleNoPort, TestPrintConfigDefaultAnnotation,
  TestPrintConfigOverrideAnnotation, TestPrintConfigAutoAssignedAnnotation

config/config_test.go

@@ -392,6 +392,172 @@ class = "MyDeterministicClass"
 	}
 }
 
+// --- PrintConfig tests ---
+
+// TestPrintConfigContainsAllClasses: defaults LoadResult produces output with all 14 class names.
+func TestPrintConfigContainsAllClasses(t *testing.T) {
+	t.Chdir(t.TempDir())
+	result, err := config.Load("")
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	classNames := []string{
+		"ICMP", "DNS", "HTTPS", "HTTP", "SSH", "SMTP",
+		"NTP", "DHCP", "other-TCP", "other-UDP",
+		"unknown-1", "unknown-2", "unknown-3", "unknown-4",
+	}
+	for _, name := range classNames {
+		if !strings.Contains(output, name) {
+			t.Errorf("PrintConfig output missing class %q", name)
+		}
+	}
+}
+
+// TestPrintConfigSourcePath: LoadResult with ConfigPath set shows the path in header.
+func TestPrintConfigSourcePath(t *testing.T) {
+	path := writeTOML(t, "[sounds.ICMP]\nfrequency = 100.0\n")
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	if !strings.Contains(output, "# Config source: "+path) {
+		t.Errorf("expected output to contain '# Config source: %s', got:\n%s", path, output)
+	}
+}
+
+// TestPrintConfigNoSourcePath: LoadResult with no ConfigPath shows "none" in header.
+func TestPrintConfigNoSourcePath(t *testing.T) {
+	t.Chdir(t.TempDir())
+	result, err := config.Load("")
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	if !strings.Contains(output, "# Config source: none") {
+		t.Errorf("expected output to contain '# Config source: none', got:\n%s", output)
+	}
+}
+
+// TestPrintConfigContainsRules: LoadResult with user rules emits [[rules]] section.
+func TestPrintConfigContainsRules(t *testing.T) {
+	tomlContent := `
+[[rules]]
+port = 8080
+protocol = "tcp"
+class = "MyApp"
+`
+	path := writeTOML(t, tomlContent)
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	if !strings.Contains(output, "[[rules]]") {
+		t.Errorf("expected output to contain '[[rules]]', got:\n%s", output)
+	}
+	if !strings.Contains(output, "port = 8080") {
+		t.Errorf("expected output to contain 'port = 8080', got:\n%s", output)
+	}
+	if !strings.Contains(output, `protocol = "tcp"`) {
+		t.Errorf("expected output to contain 'protocol = \"tcp\"', got:\n%s", output)
+	}
+	if !strings.Contains(output, `class = "MyApp"`) {
+		t.Errorf("expected output to contain 'class = \"MyApp\"', got:\n%s", output)
+	}
+}
+
+// TestPrintConfigRuleNoPort: rule with DstPort==0 omits port line in output.
+func TestPrintConfigRuleNoPort(t *testing.T) {
+	tomlContent := `
+[[rules]]
+protocol = "udp"
+class = "AllUDP"
+`
+	path := writeTOML(t, tomlContent)
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	// Find the [[rules]] block and check no port line follows before the next blank line
+	rulesIdx := strings.Index(output, "[[rules]]")
+	if rulesIdx < 0 {
+		t.Fatal("expected [[rules]] in output")
+	}
+	rulesSection := output[rulesIdx:]
+	// Extract until the next blank line after [[rules]]
+	lines := strings.Split(rulesSection, "\n")
+	for _, line := range lines {
+		if strings.HasPrefix(strings.TrimSpace(line), "port =") {
+			t.Errorf("expected no 'port =' line for rule with DstPort=0, got line: %q", line)
+		}
+		if line == "" {
+			break // end of this rule block
+		}
+	}
+}
+
+// TestPrintConfigDefaultAnnotation: default ICMP entry annotated as (default).
+func TestPrintConfigDefaultAnnotation(t *testing.T) {
+	t.Chdir(t.TempDir())
+	result, err := config.Load("")
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	if !strings.Contains(output, "(default)") {
+		t.Errorf("expected '(default)' annotation in output, got:\n%s", output)
+	}
+	// Specifically check ICMP line
+	if !strings.Contains(output, "ICMP") {
+		t.Errorf("expected ICMP in output")
+	}
+}
+
+// TestPrintConfigOverrideAnnotation: ICMP with changed BaseHz annotated as (override).
+func TestPrintConfigOverrideAnnotation(t *testing.T) {
+	path := writeTOML(t, "[sounds.ICMP]\nfrequency = 100.0\n")
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	// Find the ICMP comment line and check annotation
+	lines := strings.Split(output, "\n")
+	for _, line := range lines {
+		if strings.Contains(line, "# ICMP") {
+			if !strings.Contains(line, "(override)") {
+				t.Errorf("expected ICMP comment to contain '(override)', got: %q", line)
+			}
+			return
+		}
+	}
+	t.Error("did not find ICMP comment line in output")
+}
+
+// TestPrintConfigAutoAssignedAnnotation: user-defined class gets (auto-assigned) annotation.
+func TestPrintConfigAutoAssignedAnnotation(t *testing.T) {
+	tomlContent := `
+[[rules]]
+protocol = "tcp"
+class = "GameServer"
+`
+	path := writeTOML(t, tomlContent)
+	result, err := config.Load(path)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	output := config.PrintConfig(result)
+	if !strings.Contains(output, "(auto-assigned)") {
+		t.Errorf("expected '(auto-assigned)' annotation in output, got:\n%s", output)
+	}
+	if !strings.Contains(output, "GameServer") {
+		t.Errorf("expected GameServer in output")
+	}
+}
+
 // TestAutoFreqSkipsBuiltins: TOML with [[rules]] (class="HTTPS", protocol="tcp", port=443)
 // -> FreqCfgs["HTTPS"].BaseHz == 175.0 (the default), NOT an auto-assigned value.
 func TestAutoFreqSkipsBuiltins(t *testing.T) {