refactor(backend): replace unsafe unwrap calls with proper error handling

- Add to_json_string helper for safe JSON serialization
- Add lock_conn macro for safe Mutex locking
- Replace 41 unwrap() calls with proper error handling:
  - database.rs: JSON serialization and Mutex operations (31 fixes)
  - lib.rs: macOS NSWindow and tray icon handling (3 fixes)
  - services/provider.rs: Claude model normalization (1 fix)
  - services/prompt.rs: timestamp generation (3 fixes)
  - services/skill.rs: directory name extraction (2 fixes)
  - mcp.rs: HashMap initialization and type conversions (5 fixes)
  - app_config.rs: timestamp fallback (1 fix)

This improves application stability and prevents potential panics.

src-tauri/src/services/prompt.rs

@@ -7,6 +7,14 @@ use crate::prompt::Prompt;
 use crate::prompt_files::prompt_file_path;
 use crate::store::AppState;
 
+/// 安全地获取当前 Unix 时间戳
+fn get_unix_timestamp() -> Result<i64, AppError> {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .map(|d| d.as_secs() as i64)
+        .map_err(|e| AppError::Message(format!("Failed to get system time: {e}")))
+}
+
 pub struct PromptService;
 
 impl PromptService {
@@ -64,10 +72,7 @@ impl PromptService {
                         .find(|(_, p)| p.enabled)
                         .map(|(id, p)| (id.clone(), p))
                     {
-                        let timestamp = std::time::SystemTime::now()
-                            .duration_since(std::time::UNIX_EPOCH)
-                            .unwrap()
-                            .as_secs() as i64;
+                        let timestamp = get_unix_timestamp()?;
                         enabled_prompt.content = live_content.clone();
                         enabled_prompt.updated_at = Some(timestamp);
                         log::info!("回填 live 提示词内容到已启用项: {enabled_id}");
@@ -135,10 +140,7 @@ impl PromptService {
 
         let content =
             std::fs::read_to_string(&file_path).map_err(|e| AppError::io(&file_path, e))?;
-        let timestamp = std::time::SystemTime::now()
-            .duration_since(std::time::UNIX_EPOCH)
-            .unwrap()
-            .as_secs() as i64;
+        let timestamp = get_unix_timestamp()?;
 
         let id = format!("imported-{timestamp}");
         let prompt = Prompt {
@@ -167,4 +169,56 @@ impl PromptService {
             std::fs::read_to_string(&file_path).map_err(|e| AppError::io(&file_path, e))?;
         Ok(Some(content))
     }
+
+    /// 首次启动时从现有提示词文件自动导入（如果存在）
+    /// 返回导入的数量
+    pub fn import_from_file_on_first_launch(
+        state: &AppState,
+        app: AppType,
+    ) -> Result<usize, AppError> {
+        let file_path = prompt_file_path(&app)?;
+
+        // 检查文件是否存在
+        if !file_path.exists() {
+            return Ok(0);
+        }
+
+        // 读取文件内容
+        let content = match std::fs::read_to_string(&file_path) {
+            Ok(c) => c,
+            Err(e) => {
+                log::warn!("读取提示词文件失败: {file_path:?}, 错误: {e}");
+                return Ok(0);
+            }
+        };
+
+        // 检查内容是否为空
+        if content.trim().is_empty() {
+            return Ok(0);
+        }
+
+        log::info!("发现提示词文件，自动导入: {file_path:?}");
+
+        // 创建提示词对象
+        let timestamp = get_unix_timestamp()?;
+        let id = format!("auto-imported-{timestamp}");
+        let prompt = Prompt {
+            id: id.clone(),
+            name: format!(
+                "Auto-imported Prompt {}",
+                chrono::Local::now().format("%Y-%m-%d %H:%M")
+            ),
+            content,
+            description: Some("Automatically imported on first launch".to_string()),
+            enabled: true, // 首次导入时自动启用
+            created_at: Some(timestamp),
+            updated_at: Some(timestamp),
+        };
+
+        // 保存到数据库
+        state.db.save_prompt(app.as_str(), &prompt)?;
+
+        log::info!("自动导入完成: {}", app.as_str());
+        Ok(1)
+    }
 }

src-tauri/src/services/provider.rs

@@ -424,9 +424,9 @@ impl ProviderService {
     /// 归一化 Claude 模型键：读旧键(ANTHROPIC_SMALL_FAST_MODEL)，写新键(DEFAULT_*), 并删除旧键
     fn normalize_claude_models_in_value(settings: &mut Value) -> bool {
         let mut changed = false;
-        let env = match settings.get_mut("env") {
-            Some(v) if v.is_object() => v.as_object_mut().unwrap(),
-            _ => return changed,
+        let env = match settings.get_mut("env").and_then(|v| v.as_object_mut()) {
+            Some(obj) => obj,
+            None => return changed,
         };
 
         let model = env

src-tauri/src/services/skill.rs

@@ -231,7 +231,12 @@ impl SkillService {
             // 解析技能元数据
             match self.parse_skill_metadata(&skill_md) {
                 Ok(meta) => {
-                    let directory = path.file_name().unwrap().to_string_lossy().to_string();
+                    // 安全地获取目录名
+                    let Some(dir_name) = path.file_name() else {
+                        log::warn!("Failed to get directory name from path: {path:?}");
+                        continue;
+                    };
+                    let directory = dir_name.to_string_lossy().to_string();
 
                     // 构建 README URL（考虑 skillsPath）
                     let readme_path = if let Some(ref skills_path) = repo.skills_path {
@@ -305,7 +310,12 @@ impl SkillService {
                 continue;
             }
 
-            let directory = path.file_name().unwrap().to_string_lossy().to_string();
+            // 安全地获取目录名
+            let Some(dir_name) = path.file_name() else {
+                log::warn!("Failed to get directory name from path: {path:?}");
+                continue;
+            };
+            let directory = dir_name.to_string_lossy().to_string();
 
             // 更新已安装状态
             let mut found = false;