feat: prisma schema, groups API, deploy workflow

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

@@ -0,0 +1,17 @@
+import { requireAuth } from '~/server/utils/auth'
+import { groups, userGroups } from '~/server/utils/db'
+
+export default defineEventHandler(async (event) => {
+  const user = requireAuth(event)
+  const groupId = getRouterParam(event, 'id')!
+
+  const group = groups.get(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' })
+
+  userGroups.delete(key)
+  return { success: true, message: `Left group "${group.name}"` }
+})