Add golangci-lint v2 config and fix test idioms

Add .golangci.yml to configure linter for v2: exclude Close/Remove
from errcheck, disable pedantic staticcheck rules.
Use t.Setenv instead of manual os.Setenv/defer in tests.

Author: glebovdev

.golangci.yml

@@ -0,0 +1,17 @@
+version: "2"
+
+linters:
+  default: standard
+  settings:
+    staticcheck:
+      checks:
+        - "all"
+        - "-ST1000"
+        - "-ST1003"
+        - "-QF*"
+  exclusions:
+    rules:
+      - text: "Error return value of .+Close"
+        linters: [errcheck]
+      - text: "Error return value of `os.Remove`"
+        linters: [errcheck]

internal/cache/cache_test.go

@@ -29,7 +29,7 @@ func TestHashURL(t *testing.T) {
 			}
 
 			for _, c := range result {
-				if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f')) {
+				if (c < '0' || c > '9') && (c < 'a' || c > 'f') {
 					t.Errorf("hashURL(%q) contains non-hex character: %c", tt.url, c)
 				}
 			}

internal/config/config_test.go

@@ -24,9 +24,7 @@ func TestDefaultConfig(t *testing.T) {
 
 func TestConfigSaveAndLoad(t *testing.T) {
 	tmpDir := t.TempDir()
-	originalHome := os.Getenv("HOME")
-	os.Setenv("HOME", tmpDir)
-	defer os.Setenv("HOME", originalHome)
+	t.Setenv("HOME", tmpDir)
 
 	testCfg := &Config{
 		Volume:      85,
@@ -59,9 +57,7 @@ func TestConfigSaveAndLoad(t *testing.T) {
 
 func TestLoadNonExistentConfig(t *testing.T) {
 	tmpDir := t.TempDir()
-	originalHome := os.Getenv("HOME")
-	os.Setenv("HOME", tmpDir)
-	defer os.Setenv("HOME", originalHome)
+	t.Setenv("HOME", tmpDir)
 
 	cfg, err := Load()
 	if err != nil {
@@ -94,9 +90,7 @@ func TestVolumeValidation(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			tmpDir := t.TempDir()
-			originalHome := os.Getenv("HOME")
-			os.Setenv("HOME", tmpDir)
-			defer os.Setenv("HOME", originalHome)
+			t.Setenv("HOME", tmpDir)
 
 			testCfg := &Config{
 				Volume:      tt.inputVolume,
@@ -122,9 +116,7 @@ func TestVolumeValidation(t *testing.T) {
 
 func TestThemeDefaults(t *testing.T) {
 	tmpDir := t.TempDir()
-	originalHome := os.Getenv("HOME")
-	os.Setenv("HOME", tmpDir)
-	defer os.Setenv("HOME", originalHome)
+	t.Setenv("HOME", tmpDir)
 
 	cfg, err := Load()
 	if err != nil {
@@ -150,9 +142,7 @@ func TestThemeDefaults(t *testing.T) {
 
 func TestThemePersistence(t *testing.T) {
 	tmpDir := t.TempDir()
-	originalHome := os.Getenv("HOME")
-	os.Setenv("HOME", tmpDir)
-	defer os.Setenv("HOME", originalHome)
+	t.Setenv("HOME", tmpDir)
 
 	testCfg := &Config{
 		Volume:      70,
@@ -414,9 +404,7 @@ func TestGetColor(t *testing.T) {
 
 func TestFavoritesPersistence(t *testing.T) {
 	tmpDir := t.TempDir()
-	originalHome := os.Getenv("HOME")
-	os.Setenv("HOME", tmpDir)
-	defer os.Setenv("HOME", originalHome)
+	t.Setenv("HOME", tmpDir)
 
 	testCfg := &Config{
 		Volume:    70,
@@ -448,9 +436,7 @@ func TestFavoritesPersistence(t *testing.T) {
 
 func TestAutostartPersistence(t *testing.T) {
 	tmpDir := t.TempDir()
-	originalHome := os.Getenv("HOME")
-	os.Setenv("HOME", tmpDir)
-	defer os.Setenv("HOME", originalHome)
+	t.Setenv("HOME", tmpDir)
 
 	testCfg := &Config{
 		Volume:      70,
@@ -476,9 +462,7 @@ func TestAutostartPersistence(t *testing.T) {
 
 func TestLoadInvalidYAML(t *testing.T) {
 	tmpDir := t.TempDir()
-	originalHome := os.Getenv("HOME")
-	os.Setenv("HOME", tmpDir)
-	defer os.Setenv("HOME", originalHome)
+	t.Setenv("HOME", tmpDir)
 
 	configDir := filepath.Join(tmpDir, ConfigDir)
 	_ = os.MkdirAll(configDir, 0755)