Add first-class ebook request support and UI

Implements first-class ebook requests with their own type, parent-child relationship to audiobook requests, and separate status flow. Updates database schema and migrations to support 'type' and 'parentRequestId' fields on requests. Adds processors and job types for ebook search and direct HTTP download from Anna's Archive, with FlareSolverr integration for Cloudflare bypass. Enhances admin UI tables and request actions to display and manage ebook requests, including orange badge and source links. Updates documentation to reflect new ebook support, configuration, and behavior.

src/lib/bookdate/helpers.ts

@@ -927,7 +927,7 @@ export async function isInLibrary(
 }
 
 /**
- * Check if book has already been requested
+ * Check if book has already been requested (audiobook request)
  * @param userId - User ID
  * @param asin - Audible ASIN
  * @returns true if book is already requested
@@ -939,6 +939,8 @@ export async function isAlreadyRequested(
   const request = await prisma.request.findFirst({
     where: {
       userId,
+      type: 'audiobook', // Only check audiobook requests (ebook requests are separate)
+      deletedAt: null, // Only check active requests
       audiobook: {
         audibleAsin: asin,
       },