feat(core): move context docs to user prompt (#10162)

Fix issue [BS-2522](https://linear.app/affine-design/issue/BS-2522).

### Why make this change?
If the user data contains illegal content, carrying the user data in the system prompt will run the risk of having the account banned.

### What Changed?
- Move the `Context Documents` to the user prompt.
- Add `withPrompt` in `QueryChatHistoriesInput` options.
- Get chat histories without prompt messages.
- Omit document context when saving messages to the `aiSessionMessage` db.

packages/frontend/apps/android/App/service/src/main/graphql/affine/schema.graphqls

@@ -1123,6 +1123,8 @@ input QueryChatHistoriesInput {
   sessionOrder: ChatHistoryOrder
 
   skip: Int
+
+  withPrompt: Boolean
 }
 
 type QuotaQueryType {