localization: Update Japanese and Korean translations; add missing Korean locale files

- Updated Japanese translations in config.json, core.json, prompts.json, and startup.json for improved clarity and accuracy.
- Added new Korean locale files for config.json, core.json, prompts.json, and startup.json to support Korean language users.
- Enhanced Chinese translations in core.json and startup.json to include missing resource not found messages and WebUI related texts.

locales/en-US/prompts.json

@@ -1,8 +1,8 @@
 {
-  "prompt.duplicate_template_name": "Prompt 模板名称 '{name}' 重复：{path_a} 与 {path_b}",
-  "prompt.format_failed": "渲染 Prompt 模板 '{name}' 失败: {error}",
-  "prompt.invalid_category": "Prompt 分类 '{category}' 非法",
-  "prompt.invalid_name": "Prompt 名称 '{name}' 非法",
-  "prompt.missing_placeholder": "Prompt 模板 '{name}' 缺少占位符 '{placeholder}'",
-  "prompt.template_not_found": "未找到 locale '{locale}' 下的 Prompt 模板 '{name}'"
+  "prompt.duplicate_template_name": "Prompt template name '{name}' is duplicated: {path_a} and {path_b}",
+  "prompt.format_failed": "Failed to render prompt template '{name}': {error}",
+  "prompt.invalid_category": "Prompt category '{category}' is invalid",
+  "prompt.invalid_name": "Prompt name '{name}' is invalid",
+  "prompt.missing_placeholder": "Prompt template '{name}' is missing placeholder '{placeholder}'",
+  "prompt.template_not_found": "Prompt template '{name}' not found under locale '{locale}'"
 }