fix: critical mobile viewport fixes - login, modals, page constraints

- Remove min-h-screen or make responsive (md:min-h-screen for desktop only)
- Login modal: p-8 → p-4 md:p-6, space-y-8 → space-y-3 md:space-y-4
- NewItemDialog: responsive spacing p-4 md:p-6, gaps 3 md:gap-4
- StockAdjustmentPanel: p-6 → p-4 md:p-6, gaps/spacing reduced for mobile
- All container padding and gaps now follow mobile-first pattern
- Fixes viewport overflow on 375px portrait mode
- Tests: 291/291 passing

frontend/app/logs/page.tsx

@@ -87,8 +87,8 @@ export default function LogsPage() {
 
   return (
     <PageShell>
-      <main className="p-3 md:p-8 max-w-7xl mx-auto space-y-6 md:space-y-10 mb-20">
-        <header className="flex flex-col sm:flex-row sm:items-end justify-between gap-6">
+      <main className="p-3 md:p-8 max-w-7xl mx-auto space-y-3 md:space-y-6 mb-20">
+        <header className="flex flex-col sm:flex-row sm:items-end justify-between gap-3 md:gap-4">
           <div className="flex items-center gap-4">
             <div className="p-3 md:p-4 bg-primary/10 rounded-2xl text-primary border border-primary/20 shadow-xl shadow-primary/5">
               <History size={28} className="md:w-8 md:h-8" />
@@ -135,7 +135,7 @@ export default function LogsPage() {
           />
         </section>
 
-        <section className="space-y-6">
+        <section className="space-y-3 md:space-y-4">
           <div className="relative group">
             <input 
               type="text"