chore: 将后端移动到 api/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/task/challenge.py

@@ -0,0 +1,97 @@
+from typing import List
+from ninja import Router
+from django.shortcuts import get_object_or_404
+from account.decorators import admin_required, super_required
+from submission.models import Submission
+from .schemas import ChallengeAll, ChallengeDisplay, ChallengeIn, ChallengeSlim
+from .models import Challenge
+
+router = Router()
+
+
+@router.get("/list", response=List[ChallengeSlim])
+@admin_required
+def challenge(request):
+    """
+    后台显示所有的列表
+    """
+    return Challenge.objects.select_related("author").all()
+
+
+@router.get("/display", response=List[ChallengeDisplay])
+def get_all_public_display(request):
+    """
+    前台显示所有公开的挑战
+    """
+    challenges = list(
+        Challenge.objects.select_related("author")
+        .filter(is_public=True)
+        .order_by("-display")
+    )
+    if request.user.is_authenticated:
+        task_ids = [c.task_ptr_id for c in challenges]
+        submitted_ids = set(
+            Submission.objects.filter(
+                user=request.user,
+                task_id__in=task_ids,
+            ).values_list("task_id", flat=True)
+        )
+    else:
+        submitted_ids = set()
+    return [
+        ChallengeDisplay(
+            display=c.display,
+            title=c.title,
+            score=c.score,
+            pass_score=c.pass_score,
+            is_public=c.is_public,
+            author_name=c.author_name,
+            submitted=c.task_ptr_id in submitted_ids,
+        )
+        for c in challenges
+    ]
+
+
+@router.get("/{display}", response=ChallengeAll)
+def get(request, display: int):
+    return get_object_or_404(
+        Challenge.objects.select_related("author"), display=display
+    )
+
+
+@router.post("/")
+@admin_required
+def create_or_update(request, payload: ChallengeIn):
+    try:
+        item = Challenge.objects.get(display=payload.display)
+        item.title = payload.title
+        item.content = payload.content
+        item.score = payload.score
+        item.is_public = payload.is_public
+        item.example_html = payload.example_html
+        item.example_css = payload.example_css
+        item.example_js = payload.example_js
+        if item.author_id is None and request.user.is_authenticated:
+            item.author = request.user
+        item.save()
+        return {"message": "更新成功"}
+    except Challenge.DoesNotExist:
+        Challenge.objects.create(**payload.dict(), author=request.user)
+        return {"message": "创建成功"}
+
+
+@router.put("/public/{display}")
+@super_required
+def toggle_public(request, display: int):
+    item = get_object_or_404(Challenge, display=display)
+    item.is_public = not item.is_public
+    item.save()
+    label = "公开" if item.is_public else "隐藏"
+    return {"message": f"【{item.display}】{item.title} 已{label}"}
+
+
+@router.delete("/{display}")
+@admin_required
+def remove(request, display: int):
+    Challenge.objects.filter(display=display).delete()
+    return {"message": "删除成功"}