webui: RSS + Search tab management UI

Wire the RSS and Search tabs to the new backend:

- RSS: add/remove feeds, per-article "Add" (download), and a full
  auto-download rule editor (match/regex, must[-not]-contain, per-feed
  scope, category, save path, paused) with edit/delete.
- Search: results now add via the server-side download endpoint
  (magnet/.torrent); add a Torznab indexer manager (list/add/remove).
- api.js: feed/rule/indexer/download client methods.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/js/api.js

@@ -43,6 +43,13 @@ export const api = {
 
   rss: () => jget('/api/rss'),
   rssRules: () => jget('/api/rss/rules'),
+  addFeed: (name, url) => jpost('/api/rss', { name, url }),
+  deleteFeed: (name) => jpost('/api/rss/delete', { name }),
+  saveRssRule: (rule) => jpost('/api/rss/rules', rule),
+  deleteRssRule: (name) => jpost('/api/rss/rules/delete', { name }),
+  rssDownload: (item) => jpost('/api/rss/download', item),
+  saveIndexer: (ix) => jpost('/api/indexers', ix),
+  deleteIndexer: (name) => jpost('/api/indexers/delete', { name }),
   script: () => jget('/api/script'),
   saveScript: (source) => jpost('/api/script', { source }),
   saveScriptSettings: (settings) => jpost('/api/script/settings', { settings }),