feat(search): ✨ add proper DB tag searching

www/src/db_handler/db_interface.php

@@ -80,6 +80,16 @@ interface PostdataInterface {
         $order_by = 'path');
     
     public function get_post_markdown($id);
+
+
+    // Returns an array of PostData information
+    // based on the tag search list
+    //
+    // Tag searchlist is comprised of space-separated
+    // tags. Each tag can have a weighting prefix,
+    // and some special tags exist (such as limit:N,
+    // order:S).
+    public function search_posts($taglist);
 }
 
 ?>