feat: migrate Canvas and Groups API to Prisma ORM

app/server/api/groups/[id]/leave.post.ts

@@ -1,17 +1,20 @@
 import { requireAuth } from '~/server/utils/auth'
-import { groups, userGroups } from '~/server/utils/db'
+import { prisma } from '~/server/utils/prisma'
 
 export default defineEventHandler(async (event) => {
   const user = requireAuth(event)
   const groupId = getRouterParam(event, 'id')!
 
-  const group = groups.get(groupId)
+  const group = await prisma.group.findUnique({ where: { id: groupId } })
   if (!group) throw createError({ statusCode: 404, message: 'Group not found' })
   if (group.ownerId === user.id) throw createError({ statusCode: 400, message: 'Owner cannot leave group. Delete it instead.' })
 
-  const key = `${user.id}-${groupId}`
-  if (!userGroups.has(key)) throw createError({ statusCode: 400, message: 'Not a member' })
+  const membership = await prisma.groupMember.findUnique({
+    where: { userId_groupId: { userId: user.id, groupId } }
+  })
+  if (!membership) throw createError({ statusCode: 400, message: 'Not a member' })
+
+  await prisma.groupMember.delete({ where: { id: membership.id } })
 
-  userGroups.delete(key)
   return { success: true, message: `Left group "${group.name}"` }
 })