feat(go-config): multi-format codecs, envc CLI, fixtures, ASRs

- Module github.com/eslider/go-config with env/yaml/json/ini packages
- internal: source, keymap, merge, structconv, bytesutil
- cmd/envc: convert, get, merge
- docs/asr ASR-0001..0008, README/CHANGELOG/AGENTS refresh
- golangci-lint v2 config; tests + fixtures

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

cmd/envc/convert_test.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestRunConvert_YAMLToJSON(t *testing.T) {
+	var stdout, stderr bytes.Buffer
+	stdin := strings.NewReader("a: 1\n")
+	code := RunConvert([]string{"--from", "yaml", "--to", "json", "--input", "-"}, stdin, &stdout, &stderr)
+	if code != 0 {
+		t.Fatalf("stderr: %s", stderr.String())
+	}
+	if !strings.Contains(stdout.String(), `"a"`) {
+		t.Fatalf("out: %s", stdout.String())
+	}
+}
+
+func TestRunGet(t *testing.T) {
+	var stdout, stderr bytes.Buffer
+	in := "service:\n  name: x\n"
+	code := RunGet([]string{"--from", "yaml", "--path", "service.name", "-"}, strings.NewReader(in), &stdout, &stderr)
+	if code != 0 {
+		t.Fatalf("stderr: %s", stderr.String())
+	}
+	if strings.TrimSpace(stdout.String()) != "x" {
+		t.Fatalf("got %q", stdout.String())
+	}
+}
+
+func TestRunMerge_TwoYAMLFiles(t *testing.T) {
+	dir := t.TempDir()
+	f1 := filepath.Join(dir, "a.yaml")
+	f2 := filepath.Join(dir, "b.yaml")
+	if err := os.WriteFile(f1, []byte("k: 1\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(f2, []byte("k: 2\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	var stdout, stderr bytes.Buffer
+	code := RunMerge([]string{"--from", "yaml", "--to", "json", f1, f2}, strings.NewReader(""), &stdout, &stderr)
+	if code != 0 {
+		t.Fatalf("stderr: %s", stderr.String())
+	}
+	if !strings.Contains(stdout.String(), `"k"`) || !strings.Contains(stdout.String(), `2`) {
+		t.Fatalf("out: %s", stdout.String())
+	}
+}