Fix sidebar toggle, ? shortcut, footer hint styling

- Sidebar: replace 32px overflow:hidden collapse with display:none — eliminates pointer-event/layout issues; button label toggles between 'Filters' and 'Show Filters'
- Keyboard shortcut ?: fix keydown handler to omit shift+ prefix for symbol keys (shift state already encoded in e.key), so '?' registration matches correctly
- Footer: add missing CSS for .lt-footer-hint, .lt-footer-key, .lt-footer-sep — resets button defaults so CFG/HELP render identically to link-style hints

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

views/DashboardView.php

@@ -409,12 +409,6 @@ include __DIR__ . '/layout_header.php';
   <aside class="lt-sidebar" id="lt-sidebar" role="complementary" aria-label="Filter options">
     <div class="lt-sidebar-header">
       <span>Filters</span>
-      <button type="button" class="lt-sidebar-toggle"
-              data-action="toggle-sidebar"
-              data-sidebar-toggle="lt-sidebar"
-              aria-label="Collapse filter sidebar"
-              aria-expanded="true"
-              aria-controls="lt-sidebar">&#x25C0;</button>
     </div>
     <div class="lt-sidebar-body" id="dashboardSidebar">
 
@@ -506,6 +500,8 @@ include __DIR__ . '/layout_header.php';
     <!-- Toolbar: search + export + count -->
     <div class="lt-toolbar">
       <div class="lt-toolbar-left">
+        <button type="button" id="lt-sidebar-toggle-btn" class="lt-btn lt-btn-ghost lt-btn-sm"
+                aria-label="Toggle filter sidebar" title="Toggle filters">&#x22EE;&#x22EE; Filters</button>
         <form method="GET" action="" class="lt-search-form" role="search">
           <?php foreach (['status','category','type','sort','dir'] as $p): ?>
             <?php if (isset($_GET[$p])): ?>