Move fastext nav to page top, fix Settings header, add working search

- Fastext colour keys now lead every page but the index, since they're
  the only nav those pages carry; the index keeps them as its closing
  row since its own body is already the full nav.
- Settings page was missing page="settings" in its render_template
  call, so its header silently fell back to "P100 Index".
- Library's search form posted a q param the route never read; it now
  filters the cached Sonarr/Radarr lists and shows matching tiles.
- Discover gained a search bar that queries Ombi (already in front of
  TMDB/TVDB) and lets you add a result straight to Radarr/Sonarr,
  showing "Held" instead of a button for anything already in library.
- Fixed the Add button's success check, which read d.ok against a
  response that actually sets d.success — it reported FAILED even
  when the add worked.

templates/_shell.html

@@ -45,19 +45,28 @@ provenance.
     <span class="tt-head-clock" id="head-clock"></span>
   </header>
 
-  <main class="tt-page">
-    {% block content %}{% endblock %}
-  </main>
-
   {#- Fastext: the four coloured keys. Each page names its own four, so the
-      keys always point somewhere useful from where you are. -#}
-  <nav class="fastext" aria-label="Fastext">
+      keys always point somewhere useful from where you are. On the index
+      it stays the closing row, under Now Showing/Just Added, since the
+      index's own body already is the full nav. Everywhere else it leads,
+      right under the header, since it's the only nav those pages carry. -#}
+  {% set fastext_nav %}
+  <nav class="fastext{{ '' if page == 'home' else ' fastext-top' }}" aria-label="Fastext">
     {% for cls, key, num, label, href in fastext %}
     <a class="{{ cls }}" href="{{ request.script_root }}{{ href }}" data-key="{{ key }}">
       <span>{{ num }} {{ label }}</span>
     </a>
     {% endfor %}
   </nav>
+  {% endset %}
+
+  {% if page != 'home' %}{{ fastext_nav }}{% endif %}
+
+  <main class="tt-page">
+    {% block content %}{% endblock %}
+  </main>
+
+  {% if page == 'home' %}{{ fastext_nav }}{% endif %}
 
   <footer class="tt-foot">
     <span>MEDIA CENTRE</span>