feat: 支持多语言提示词本地化和界面优化

- 添加 prompt_locale 参数支持简体中文、繁体中文和英文提示词本地化
- 移除内置 agents 配置以简化系统架构
- 更新 ContextBuilder 使用动态提示词模板而非硬编码内容
- 在 AgentLoop、Web 接口和 AgentService 中传递 locale 参数
- 添加输出语言指令确保用户界面内容按指定语言生成
- 扩展前端 LanguageSwitcher 组件支持三种语言选项
- 优化 Header 和侧边栏组件的响应式布局和文本截断处理
- 更新测试用例验证不同语言环境下的提示词正确性

app-instance/backend/beaver/prompts/main_agent.py

@@ -0,0 +1,55 @@
+"""Locale-aware main agent prompt loading."""
+
+from __future__ import annotations
+
+from functools import lru_cache
+from pathlib import Path
+
+DEFAULT_MAIN_AGENT_PROMPT_LOCALE = "zh-Hans"
+
+_PROMPT_FILES = {
+    "zh-Hans": "zh-Hans.md",
+    "zh-Hant": "zh-Hant.md",
+    "en": "en.md",
+}
+
+_LOCALE_ALIASES = {
+    "zh": "zh-Hans",
+    "zh-cn": "zh-Hans",
+    "zh-hans": "zh-Hans",
+    "zh-sg": "zh-Hans",
+    "zh-hant": "zh-Hant",
+    "zh-tw": "zh-Hant",
+    "zh-hk": "zh-Hant",
+    "zh-mo": "zh-Hant",
+    "en": "en",
+    "en-us": "en",
+    "en-gb": "en",
+}
+
+
+def get_main_agent_prompt(locale: str | None = None) -> str:
+    """Return the main-agent identity prompt for a prompt locale."""
+
+    prompt_locale = normalize_main_agent_prompt_locale(locale)
+    return _load_main_agent_prompt(prompt_locale)
+
+
+def normalize_main_agent_prompt_locale(locale: str | None = None) -> str:
+    cleaned = (locale or DEFAULT_MAIN_AGENT_PROMPT_LOCALE).strip()
+    if not cleaned:
+        return DEFAULT_MAIN_AGENT_PROMPT_LOCALE
+    normalized = _LOCALE_ALIASES.get(cleaned.lower())
+    if normalized:
+        return normalized
+    return cleaned if cleaned in _PROMPT_FILES else DEFAULT_MAIN_AGENT_PROMPT_LOCALE
+
+
+@lru_cache(maxsize=len(_PROMPT_FILES))
+def _load_main_agent_prompt(locale: str) -> str:
+    filename = _PROMPT_FILES.get(locale, _PROMPT_FILES[DEFAULT_MAIN_AGENT_PROMPT_LOCALE])
+    path = Path(__file__).with_name("main_agent") / filename
+    if not path.exists():
+        fallback_path = Path(__file__).with_name("main_agent") / _PROMPT_FILES[DEFAULT_MAIN_AGENT_PROMPT_LOCALE]
+        return fallback_path.read_text(encoding="utf-8").strip()
+    return path.read_text(encoding="utf-8").strip()