Add skip-unreleased auto-search feature

Introduce an indexer-wide option to skip automatic searches for books with future release dates (config key: `indexer.skip_unreleased`, default ON). Adds a GET/PUT admin API for indexer options, a UI toggle on the Indexers settings tab (persisted on save), and persistence of a request-level releaseDate in the Prisma schema.

Adds a new request status `awaiting_release` and wires it through constants, UI components (StatusBadge, RequestCard, RecentRequestsTable, Audiobook card/modal, RequestActions), API request flows (bookdate swipe, request creation, manual search, request PATCHs, request listing groups), and services. Implements a pure release-date utility (isUnreleased / shouldSkipAutoSearch) and updates background processors: monitor-rss-feeds (skip matches but do not mutate status), retry-missing-torrents (drives bidirectional transitions between awaiting_search and awaiting_release and queues searches when appropriate), and request-creator/bookdate swipe (gate initial auto-search). Adds tests for the swipe gate and other related test updates. Logs transitions and gate decisions for observability.

documentation/TABLEOFCONTENTS.md

@@ -59,6 +59,7 @@
 - **Ebook delete behavior (files only, torrents seed)** → [integrations/ebook-sidecar.md](integrations/ebook-sidecar.md#delete-behavior)
 - **Ebook settings (3-section UI)** → [settings-pages.md](settings-pages.md#e-book-sidecar)
 - **Indexer categories (audiobook/ebook tabs)** → [settings-pages.md](settings-pages.md#indexer-categories-tabbed)
+- **Auto-search behavior toggle (skip unreleased books)** → [settings-pages.md](settings-pages.md#auto-search-behavior-indexers-tab)
 
 ## Automation Pipeline
 - **Full pipeline overview** → [phase3/README.md](phase3/README.md)