chore: baseline snapshot before moderation-strictness feature

Repo .git was damaged (refs/ missing, index truncated, object store near-empty).
Repaired via git init (rebuilt refs), stale index preserved as .git/index.corrupt-20260910.bak,
then full worktree committed as a rollback baseline.

internal/shared/state_test.go

@@ -0,0 +1,77 @@
+package shared
+
+import (
+	"testing"
+	"time"
+
+	"github.com/tamakyi/TamaBox/internal/i18n"
+)
+
+func TestAppState_Default(t *testing.T) {
+	s := NewAppState()
+	if got := s.Lang(); got != i18n.Default {
+		t.Errorf("默认语言 = %q, 期望 %q", got, i18n.Default)
+	}
+}
+
+func TestAppState_SetLang_Normalize(t *testing.T) {
+	cases := []struct {
+		in   string
+		want string
+	}{
+		{"zh-CN", i18n.LangZhCN},
+		{"zh_CN", i18n.LangZhCN}, // 下划线变体
+		{"zh", i18n.LangZhCN},
+		{"zh-TW", i18n.LangZhTW},
+		{"zh_hk", i18n.LangZhTW}, // 港繁统一映射到繁体中文
+		{"zh-hant", i18n.LangZhTW},
+		{"en", i18n.LangEn},
+		{"en-US", i18n.LangEn},
+		{"ja", i18n.LangJa},
+		{"ja_JP", i18n.LangJa},
+		{"  En  ", i18n.LangEn}, // 自动去空白
+		{"fr", i18n.Default},    // 未知回退
+		{"", i18n.Default},      // 空值回退
+	}
+
+	for _, tc := range cases {
+		s := NewAppState()
+		s.SetLang(tc.in)
+		if got := s.Lang(); got != tc.want {
+			t.Errorf("SetLang(%q) 后 Lang() = %q, 期望 %q", tc.in, got, tc.want)
+		}
+	}
+}
+
+func TestAppState_Concurrent(t *testing.T) {
+	s := NewAppState()
+	const n = 100
+
+	// 并发读写，覆盖 RWMutex 的多读单写路径。
+	// 用 channel 计数替代 WaitGroup（部分受限环境对 WaitGroup 信号量支持异常）。
+	done := make(chan struct{}, n)
+	for i := 0; i < n; i++ {
+		go func(i int) {
+			defer func() { done <- struct{}{} }()
+			if i%2 == 0 {
+				s.SetLang("en")
+			} else {
+				_ = s.Lang()
+			}
+		}(i)
+	}
+	for i := 0; i < n; i++ {
+		select {
+		case <-done:
+		case <-time.After(10 * time.Second):
+			t.Fatalf("并发测试超时：仅 %d/%d 完成", i, n)
+		}
+	}
+}
+
+func TestApp_Singleton(t *testing.T) {
+	// 单例默认语言为 zh-CN
+	if App.Lang() != i18n.Default {
+		t.Errorf("App.Lang() = %q, 期望默认 %q", App.Lang(), i18n.Default)
+	}
+}