移动端拍照上传、奥数区、学段约束解题与 AI 模型配置。

- 手机/平板响应式布局，支持拍照与相册上传

- 学生详情新增奥数区，按初/高中学段生成解法并禁止超纲

- 系统设置可配置 Ollama 或 OpenAI 兼容 API

- 更新 frontend/dist 与使用说明

backend/app/services/seed.py

@@ -26,8 +26,30 @@ def seed_subjects(db: Session) -> None:
 
 
 def seed_admin_and_settings(db: Session) -> None:
-    if db.get(SystemSettings, 1) is None:
-        db.add(SystemSettings(id=1, registration_enabled=True))
+    row = db.get(SystemSettings, 1)
+    if row is None:
+        db.add(
+            SystemSettings(
+                id=1,
+                registration_enabled=True,
+                ai_provider="ollama",
+                ollama_base_url=settings.OLLAMA_BASE_URL,
+                ollama_model=settings.OLLAMA_MODEL,
+                openai_base_url=settings.OPENAI_BASE_URL,
+                openai_model=settings.OPENAI_MODEL,
+            )
+        )
+    else:
+        if not row.ollama_base_url:
+            row.ollama_base_url = settings.OLLAMA_BASE_URL
+        if not row.ollama_model:
+            row.ollama_model = settings.OLLAMA_MODEL
+        if not row.openai_base_url:
+            row.openai_base_url = settings.OPENAI_BASE_URL
+        if not row.openai_model:
+            row.openai_model = settings.OPENAI_MODEL
+        if not row.ai_provider:
+            row.ai_provider = "ollama"
 
     admin = db.query(User).filter(User.username == settings.ADMIN_DEFAULT_USERNAME).first()
     if admin is None: