Add Transmission/NZBGet and per-client paths and much more

Extend multi-download-client support to include Transmission and NZBGet and introduce per-client custom download paths. Adds protocol mapping and new client types, Transmission/NZBGet integration services, API CRUD and validation changes, UI components/modal updates and live path previews, and manager routing by protocol. Includes DB migrations (download_path on download_history, interactive_search_access on users), schema updates, and related processor/service fixes and tests to ensure backward compatibility and proper path resolution.

tests/app/admin/settings/hooks/useSettings.test.tsx

@@ -62,6 +62,7 @@ const baseSettings = {
     downloadDir: '',
     mediaDir: '',
     audiobookPathTemplate: '',
+    ebookPathTemplate: '',
     metadataTaggingEnabled: true,
     chapterMergingEnabled: false,
   },

tests/app/admin/settings/lib/helpers.test.ts

@@ -54,6 +54,7 @@ const baseSettings = {
     downloadDir: '/downloads',
     mediaDir: '/media',
     audiobookPathTemplate: '',
+    ebookPathTemplate: '',
     metadataTaggingEnabled: true,
     chapterMergingEnabled: false,
   },