fix: filter deleted tasks/list items from focus, redirect task delete to list

Focus query now excludes soft-deleted tasks and list items.
Task delete redirects to /tasks instead of back to the (now deleted)
task's edit page.

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

routers/tasks.py

@@ -427,8 +427,7 @@ async def toggle_task(task_id: str, request: Request, db: AsyncSession = Depends
 async def delete_task(task_id: str, request: Request, db: AsyncSession = Depends(get_db)):
     repo = BaseRepository("tasks", db)
     await repo.soft_delete(task_id)
-    referer = request.headers.get("referer", "/tasks")
-    return RedirectResponse(url=referer, status_code=303)
+    return RedirectResponse(url="/tasks", status_code=303)
 
 
 # Quick add from any task list