fix: remove redundant query= param from filter-specific metadata links on TFE page

Clicking orientation, AP program, finality, year, format, or keyword links
on the TFE page was passing both a dedicated filter param AND a query=
param. The query= text search doesn't look at the filter columns
(orientation, ap_program, etc.), so the AND combination yielded zero
results when the filter value didn't appear in title/authors/etc fields.

Also fix the language link: it was passing language as query= which
searches only title/authors/etc, not the languages column. Now uses
the dedicated language= param (DB layer already supported it, and
collectSearchParams now collects it).

app/src/Controllers/SearchController.php

@@ -356,6 +356,9 @@ class SearchController
         if (!empty($_GET['keyword'])) {
             $params['keyword'] = (string) $_GET['keyword'];
         }
+        if (!empty($_GET['language'])) {
+            $params['language'] = (string) $_GET['language'];
+        }
 
         return $params;
     }