refactor: migrate session management to TRPC and remove legacy API endpoints

app/src/utils/api.ts

@@ -9,17 +9,3 @@ const api = axios.create({
   withCredentials: true,
 })
 export default api
-
-export async function createSession(questId: string): Promise<Session> {
-  const res = await api.post<Session>('/sessions', { questId })
-  return res.data
-}
-
-export async function getActiveSession(
-  questId: string
-): Promise<Session | null> {
-  const res = await api.get<Session | null>('/sessions/active', {
-    params: { questId },
-  })
-  return res.data
-}