fix: prevent input field overflow on mobile by ensuring equal margins

Adds box-sizing: border-box to all filter inputs after 'all: unset' to ensure padding is included within the 100% width calculation, preventing horizontal overflow and ensuring equal left/right margins on small screens.

src/lib/components/Search.svelte

@@ -265,6 +265,7 @@
 <style>
 input#search {
   all: unset;
+  box-sizing: border-box;
   font-family: sans-serif;
   background: var(--nord0);
   color: #fff;