feat: add Prowlarr integration for manual release search

Add Prowlarr indexer integration (step 1: config + manual search).
Allows searching for comics/ebooks releases on Prowlarr indexers
directly from the series detail page, with download links and
per-volume search for missing books.

- Backend: new prowlarr module with search and test endpoints
- Migration: add prowlarr settings (url, api_key, categories)
- Settings UI: Prowlarr config card with test connection button
- ProwlarrSearchModal: auto-search on open, missing volumes shortcuts
- Fix series.readCount i18n plural parameter on series pages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/api/src/openapi.rs

@@ -58,6 +58,8 @@ use utoipa::OpenApi;
         crate::settings::list_status_mappings,
         crate::settings::upsert_status_mapping,
         crate::settings::delete_status_mapping,
+        crate::prowlarr::search_prowlarr,
+        crate::prowlarr::test_prowlarr,
     ),
     components(
         schemas(
@@ -122,6 +124,11 @@ use utoipa::OpenApi;
             crate::metadata::ExternalMetadataLinkDto,
             crate::metadata::MissingBooksDto,
             crate::metadata::MissingBookItem,
+            crate::prowlarr::ProwlarrSearchRequest,
+            crate::prowlarr::ProwlarrRelease,
+            crate::prowlarr::ProwlarrCategory,
+            crate::prowlarr::ProwlarrSearchResponse,
+            crate::prowlarr::ProwlarrTestResponse,
             ErrorResponse,
         )
     ),
@@ -135,6 +142,7 @@ use utoipa::OpenApi;
         (name = "indexing", description = "Search index management and job control (Admin only)"),
         (name = "tokens", description = "API token management (Admin only)"),
         (name = "settings", description = "Application settings and cache management (Admin only)"),
+        (name = "prowlarr", description = "Prowlarr indexer integration (Admin only)"),
     ),
     modifiers(&SecurityAddon)
 )]