Add project soft-delete with workspace archival

- Add delete button (×) to sidebar project list, shown on hover
- Soft-delete: mark projects as deleted in DB instead of hard delete
- Move workspace files to /app/data/deleted/ folder on deletion
- Filter deleted projects from list query
- Auto-select next project after deleting current one
- Also includes agent prompt improvements for reverse proxy paths

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/agent.rs

@@ -474,8 +474,13 @@ fn build_planning_prompt(project_id: &str) -> String {
         - 工作目录是独立的项目工作区，Python venv 已预先激活（.venv/）\n\
         - 可用工具：bash、git、curl、uv\n\
         - 静态文件访问：/api/projects/{0}/files/{{filename}}\n\
-        - 后台服务访问：/api/projects/{0}/app/\n\
-        - 如果要构建 Web 应用，推荐 FastAPI + 前端 HTML，API 请求用相对路径 /api/projects/{0}/app/...\n\
+        - 后台服务访问：/api/projects/{0}/app/（反向代理，路径会被转发到应用的 /）\n\
+        \n\
+        【重要】反向代理注意事项：\n\
+        - 用户通过 /api/projects/{0}/app/ 访问应用，请求被代理到应用的 / 路径\n\
+        - 因此前端 HTML 中的所有 API 请求必须使用【不带开头 / 的相对路径】\n\
+        - 正确示例：fetch('todos') 或 fetch('./todos')    错误示例：fetch('/todos') 或 fetch('/api/todos')\n\
+        - HTML 中的 <base> 标签不需要设置，只要不用绝对路径就行\n\
         \n\
         请使用中文回复。",
         project_id,
@@ -505,6 +510,7 @@ fn build_execution_prompt(project_id: &str) -> String {
         - 使用 `uv add <包名>` 或 `pip install <包名>` 安装依赖\n\
         - 静态文件访问：/api/projects/{0}/files/{{filename}}\n\
         - 后台服务访问：/api/projects/{0}/app/（启动命令需监听 0.0.0.0:$PORT）\n\
+        - 【重要】应用通过反向代理访问，前端 HTML/JS 中的 fetch/XHR 请求必须使用相对路径（如 fetch('todos')），绝对不能用 / 开头的路径（如 fetch('/todos')），否则会 404\n\
         \n\
         请使用中文回复。",
         project_id,

src/api/projects.rs

@@ -40,7 +40,7 @@ pub fn router(state: Arc<AppState>) -> Router {
 async fn list_projects(
     State(state): State<Arc<AppState>>,
 ) -> ApiResult<Vec<Project>> {
-    sqlx::query_as::<_, Project>("SELECT * FROM projects ORDER BY updated_at DESC")
+    sqlx::query_as::<_, Project>("SELECT * FROM projects WHERE deleted = 0 ORDER BY updated_at DESC")
         .fetch_all(&state.db.pool)
         .await
         .map(Json)
@@ -109,10 +109,30 @@ async fn delete_project(
     State(state): State<Arc<AppState>>,
     Path(id): Path<String>,
 ) -> ApiResult<bool> {
-    sqlx::query("DELETE FROM projects WHERE id = ?")
+    // Soft delete: mark as deleted in DB
+    let result = sqlx::query("UPDATE projects SET deleted = 1, updated_at = datetime('now') WHERE id = ? AND deleted = 0")
         .bind(&id)
         .execute(&state.db.pool)
         .await
-        .map(|r| Json(r.rows_affected() > 0))
-        .map_err(db_err)
+        .map_err(db_err)?;
+
+    if result.rows_affected() == 0 {
+        return Ok(Json(false));
+    }
+
+    // Move workspace to deleted folder
+    let src = std::path::PathBuf::from("/app/data/workspaces").join(&id);
+    let dst_dir = std::path::PathBuf::from("/app/data/deleted");
+    if src.exists() {
+        if let Err(e) = tokio::fs::create_dir_all(&dst_dir).await {
+            tracing::error!("Failed to create deleted dir: {}", e);
+        } else {
+            let dst = dst_dir.join(&id);
+            if let Err(e) = tokio::fs::rename(&src, &dst).await {
+                tracing::error!("Failed to move workspace to deleted: {}", e);
+            }
+        }
+    }
+
+    Ok(Json(true))
 }

src/db.rs

@@ -94,6 +94,13 @@ impl Database {
         .execute(&self.pool)
         .await;
 
+        // Migration: add deleted column to projects
+        let _ = sqlx::query(
+            "ALTER TABLE projects ADD COLUMN deleted INTEGER NOT NULL DEFAULT 0"
+        )
+        .execute(&self.pool)
+        .await;
+
         sqlx::query(
             "CREATE TABLE IF NOT EXISTS timers (
                 id TEXT PRIMARY KEY,
@@ -120,6 +127,8 @@ pub struct Project {
     pub description: String,
     pub created_at: String,
     pub updated_at: String,
+    #[serde(default)]
+    pub deleted: bool,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]