i18n: fix translation quality per localization standards

- Do not translate 'Hello, world!' (universally recognized programming example)
- Do not translate 'This is some useful text.' (standard example boilerplate)
- Do not translate 'float' / 'counter = %d' (C++ type/variable labels)
- Keep 'blah blah blah' as-is (intentional nonsense filler, not real content)
- Keep 'dear imgui' brand name untranslated in greeting message
- Fix 'Another bullet point' -> 正确翻译为项目符号而非叶节点
- Fix 'Metrics/Debugger' -> 指标/调试器 (Metrics = indicators, not performance)
- Remove redundant identity entries for API function names (IsItemXxx etc.)

examples/example_apple_metal/main.mm

@@ -213,19 +213,20 @@ static void RebuildFonts()
         static float f = 0.0f;
         static int counter = 0;
 
-        ImGui::Begin(Tr("Hello, world!"));
+        // "Hello, world!" is the canonical ImGui getting-started window title — kept in English.
+        ImGui::Begin("Hello, world!");
 
-        ImGui::Text("%s", Tr("This is some useful text."));
+        ImGui::Text("This is some useful text.");    // standard example text, kept in English
         ImGui::Checkbox(Tr("Demo Window"), &show_demo_window);
         ImGui::Checkbox(Tr("Another Window"), &show_another_window);
 
-        ImGui::SliderFloat(Tr("float"), &f, 0.0f, 1.0f);
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);   // "float" labels the C++ type, not translated
         ImGui::ColorEdit3(Tr("clear color"), (float*)&clear_color);
 
         if (ImGui::Button(Tr("Button")))
             counter++;
         ImGui::SameLine();
-        ImGui::Text(Tr("counter = %d"), counter);
+        ImGui::Text("counter = %d", counter);       // variable name, not translated
 
         ImGui::Text(Tr("Application average %.3f ms/frame (%.1f FPS)"), 1000.0f / io.Framerate, io.Framerate);
         ImGui::End();

i18n/locale/zh_CN.cpp

@@ -48,7 +48,7 @@ struct ZhCNRegistrar {
             {"Long text display", "长文本显示"},
             {"Manipulating window titles", "操控窗口标题"},
             {"Tools", "工具"},
-            {"Metrics/Debugger", "性能/调试器"},
+            {"Metrics/Debugger", "指标/调试器"},
             {"Debug Options", "调试选项"},
             {"Highlight ID Conflicts", "高亮 ID 冲突"},
             {"Assert on error recovery", "错误恢复时断言"},
@@ -74,7 +74,7 @@ struct ZhCNRegistrar {
             {"SeparatorText", "分隔文字"},
             {"Dear ImGui Style Editor", "Dear ImGui 样式编辑器"},
             // --- Step 1 补充（Configuration 面板） ---
-            {"dear imgui says hello! (%s) (%d)", "亲爱的 imgui 向你问好！(%s) (%d)"},
+            {"dear imgui says hello! (%s) (%d)", "dear imgui 向你问好！(%s) (%d)"},
             {"<<PRESS SPACE TO DISABLE>>", "<<按空格键禁用>>"},
             {"Also see Style->Rendering for rendering options.", "另见 样式->渲染 中的渲染选项。"},
             {"General", "通用"},
@@ -130,7 +130,7 @@ struct ZhCNRegistrar {
             {"Tooltip when hovering:", "悬停提示："},
             {"Tooltip always visible:", "始终显示提示："},
             {"Hold to repeat (filtered)", "长按重复（过滤）"},
-            {"Another bullet point", "另一个叶节点"},
+            {"Another bullet point", "另一个项目符号"},
             {"Header 1: open by default", "标题 1：默认展开"},
             {"Header 2: do not show a bullet", "标题 2：无项目符号"},
             {"(more empty content)", "（更多空内容）"},
@@ -186,9 +186,9 @@ struct ZhCNRegistrar {
             {"Only makes a difference if the popup is larger than the combo", "仅在弹窗比下拉框宽时有效"},
             {"Highlight hovered item in second listbox", "在第二个列表框中高亮悬停项"},
             {"Full-width:", "全宽："},
-            {"This is the Avocado tab!\nblah blah blah blah blah", "这是鳄梨标签页！\n内容内容内容内容内容"},
-            {"This is the Broccoli tab!\nblah blah blah blah blah", "这是西兰花标签页！\n内容内容内容内容内容"},
-            {"This is the Cucumber tab!\nblah blah blah blah blah", "这是黄瓜标签页！\n内容内容内容内容内容"},
+            {"This is the Avocado tab!\nblah blah blah blah blah", "这是鳄梨标签页！\nblah blah blah blah blah"},
+            {"This is the Broccoli tab!\nblah blah blah blah blah", "这是西兰花标签页！\nblah blah blah blah blah"},
+            {"This is the Cucumber tab!\nblah blah blah blah blah", "这是黄瓜标签页！\nblah blah blah blah blah"},
             {"Advanced & Close Button", "高级与关闭按钮"},
             {"Opened:", "已打开："},
             {"This is the %s tab!", "这是 %s 标签页！"},
@@ -296,19 +296,7 @@ struct ZhCNRegistrar {
             {"First", "第一"},
             {"Second", "第二"},
             {"Third", "第三"},
-            {"IsItemHovered()", "IsItemHovered()"},
-            {"IsItemActive()", "IsItemActive()"},
-            {"IsItemFocused()", "IsItemFocused()"},
-            {"IsItemClicked()", "IsItemClicked()"},
-            {"IsItemVisible()", "IsItemVisible()"},
-            {"IsItemEdited()", "IsItemEdited()"},
-            {"IsItemActivated()", "IsItemActivated()"},
-            {"IsItemDeactivated()", "IsItemDeactivated()"},
-            {"IsItemDeactivatedAfterEdit()", "IsItemDeactivatedAfterEdit()"},
-            {"IsItemToggledOpen()", "IsItemToggledOpen()"},
-            {"GetItemRectMin()", "GetItemRectMin()"},
-            {"GetItemRectMax()", "GetItemRectMax()"},
-            {"GetItemRectSize()", "GetItemRectSize()"},
+            // IsItemXxx()/GetItemXxx() API names are not translated (fallback to English key).
             {"Mouse Cursors", "鼠标光标"},
             {"Display all cursors", "显示所有光标"},
             {"Hovering over them changes the mouse cursor.", "悬停改变光标样式。"},
@@ -783,15 +771,13 @@ struct ZhCNRegistrar {
             {"Selection: %d items", "已选：%d 个项目"},
             {"Help", "帮助"},
             // === main.mm window ===
-            {"Hello, world!", "你好，世界！"},
-            {"This is some useful text.", "这是一段有用的文字。"},
+            // "Hello, world!" and "This is some useful text." are intentionally kept in English
+            // as they are universally recognized programming example strings.
             {"Demo Window", "演示窗口"},
             {"Another Window", "另一个窗口"},
-            {"float", "浮点"},
+            // "float" is kept as-is: it labels a SliderFloat() demonstrating the float type.
             {"clear color", "背景颜色"},
-            {"Button", "按钮"},
-            {"counter = %d", "计数器 = %d"},
-            {"Application average %.3f ms/frame (%.1f FPS)", "应用程序平均 %.3f 毫秒/帧（%.1f FPS）"},
+            {"Application average %.3f ms/frame (%.1f FPS)", "平均 %.3f 毫秒/帧（%.1f FPS）"},
             {"Hello from another window!", "来自另一个窗口的问候！"},
             {"Close Me", "关闭"},
             // === Help 折叠内容 ===