Refactor API integration and data fetching for genre, novel, and chapter pages

- Replace Prisma database calls with API fetches from the reader API in GenreDetailPage, GenresPage, SearchPage, ChapterReaderPage, and NovelDetailPage.
- Introduce new utility functions for API requests in server-api.ts, including error handling.
- Update authentication flow in auth.ts to sync Google login with the reader API.
- Modify NextAuth session and JWT types to include additional user information.
- Clean up unused imports and code related to Prisma and MongoDB connections.
- Adjust the configuration in next.config.mjs to remove unnecessary API routes.

lib/server-api.ts

@@ -0,0 +1,48 @@
+const apiBaseUrl = (process.env.READER_API_ORIGIN || "http://localhost:8000").replace(/\/+$/, "")
+
+export class ReaderApiError extends Error {
+  status: number
+
+  constructor(status: number, message: string) {
+    super(message)
+    this.status = status
+  }
+}
+
+function buildApiUrl(path: string) {
+  return `${apiBaseUrl}${path.startsWith("/") ? path : `/${path}`}`
+}
+
+export async function readerApiFetch<T>(path: string, init?: RequestInit): Promise<T> {
+  const response = await fetch(buildApiUrl(path), {
+    ...init,
+    cache: init?.cache ?? "no-store",
+    headers: {
+      Accept: "application/json",
+      ...(init?.headers || {}),
+    },
+  })
+
+  if (!response.ok) {
+    let detail = response.statusText
+    try {
+      const data = await response.json()
+      detail = data?.detail || data?.error || detail
+    } catch {}
+
+    throw new ReaderApiError(response.status, `Reader API error ${response.status}: ${detail}`)
+  }
+
+  return response.json() as Promise<T>
+}
+
+export async function readerApiFetchNullable<T>(path: string, init?: RequestInit): Promise<T | null> {
+  try {
+    return await readerApiFetch<T>(path, init)
+  } catch (error) {
+    if (error instanceof ReaderApiError && error.status === 404) {
+      return null
+    }
+    throw error
+  }
+}