Search Sonarr/Radarr directly on Discover, full top nav, live System links

- Discover's search now hits Radarr's/Sonarr's own lookup endpoints
  directly (the same ones /add-to-radarr and /add-to-sonarr already
  use), instead of Ombi — one fewer round trip, and a result always
  resolves the same way its own Add button will. The Ombi-based
  ombi_search/_tmdb_poster helpers are gone.
- The top nav on every page but the index now lists all eight
  destinations (FULL_FASTEXT) instead of the original four; the index
  keeps the original four-entry row as its own closing line
  (HOME_FASTEXT), since its body already lists every destination once.
- System page's Transmission rows are now links to each service's own
  reverse-proxied instance (service_urls, already injected into every
  template but unused until now).

templates/discover.html

@@ -7,11 +7,12 @@
   <p class="tt-empty">Popular right now, with anything already in library filtered out.</p>
 
   {#- Search sits at the top for the same reason it does on Library: a
-      title in mind is the common case. This one asks Ombi, which already
-      sits in front of TheMovieDB/TVDB, then lets you add straight to
-      Radarr/Sonarr from the result. -#}
+      title in mind is the common case. This one hits Radarr's and
+      Sonarr's own lookup directly — the same call /add-to-radarr and
+      /add-to-sonarr already make — so a result here always resolves the
+      same way a click on its own Add button will. -#}
   <form class="tt-search" action="{{ request.script_root }}/discover" method="get" role="search">
-    <label class="visually-hidden" for="q">Search Ombi for a title</label>
+    <label class="visually-hidden" for="q">Search Sonarr and Radarr for a title to add</label>
     <input class="tt-input" type="search" id="q" name="q" value="{{ q }}"
            placeholder="SEARCH TO ADD" autocomplete="off" spellcheck="false">
     <button class="tt-btn" type="submit">Search</button>
@@ -23,7 +24,7 @@
       <span class="tt-field-meta">&ldquo;{{ q }}&rdquo;</span>
     </div>
     {% if search.status != 'ok' %}
-      {{ service_error('Ombi', search.error) }}
+      {{ service_error('Sonarr/Radarr', search.error) }}
     {% elif search.results %}
       <div class="tt-tiles">
         {% for it in search.results %}