refactor: improve type safety, Svelte 5 reactivity, and API resilience

src/lib/element_qr_scanner_v2.svelte

@@ -56,6 +56,12 @@
     let show_qr_manual_entry: null | boolean = $state(null);
     let disable_submit_badge_id_btn: boolean = $state(true);
 
+    let search_query_str = $state('');
+
+    function handle_oninput_search_query_str(e: Event) {
+        search_query_str = (e.target as HTMLInputElement).value;
+    }
+
     let user_media_status = 'not_requested';
 
     let debug_comment: string = 'Debugging QR Scanner';
@@ -436,10 +442,9 @@
                     <input
                         type="text"
                         placeholder="Name or Email"
-                        label="Name or Email"
+                        aria-label="Name or Email"
                         value={search_query_str}
-                        focus={true}
-                        ononinput={handle_oninput_search_query_str}
+                        oninput={handle_oninput_search_query_str}
                     />
                 </div>
             {:else}