Add desktop sidebar toggle with persistent state, search result highlighting, and improved filter icon positioning

frontend/style.css

@@ -137,6 +137,25 @@ a:hover {
   color: var(--accent);
 }
 
+.sidebar-toggle-btn {
+  display: flex;
+  background: none;
+  border: none;
+  color: var(--text-secondary);
+  cursor: pointer;
+  padding: 4px;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+  transition: color 200ms ease;
+}
+.sidebar-toggle-btn:hover {
+  color: var(--accent);
+}
+.sidebar-toggle-btn.active {
+  color: var(--accent);
+}
+
 .header-logo {
   font-family: 'JetBrains Mono', monospace;
   font-weight: 700;
@@ -544,10 +563,17 @@ select {
   display: flex;
   flex-direction: column;
   overflow: hidden;
-  transition: background 200ms ease;
+  transition: background 200ms ease, transform 300ms ease;
   flex-shrink: 0;
 }
 
+.sidebar.hidden {
+  transform: translateX(-100%);
+  width: 0;
+  min-width: 0;
+  border-right: none;
+}
+
 
 /* --- Sidebar filter --- */
 .sidebar-filter {
@@ -557,7 +583,6 @@ select {
   flex-shrink: 0;
   display: flex;
   align-items: center;
-  gap: 6px;
 }
 
 .sidebar-filter-input-wrapper {
@@ -863,7 +888,7 @@ select {
   cursor: ew-resize;
   background: transparent;
   flex-shrink: 0;
-  transition: background 150ms ease;
+  transition: background 150ms ease, opacity 300ms ease;
   z-index: 10;
 }
 .sidebar-resize-handle:hover,
@@ -871,6 +896,11 @@ select {
   background: var(--accent);
   opacity: 0.5;
 }
+.sidebar-resize-handle.hidden {
+  width: 0;
+  opacity: 0;
+  pointer-events: none;
+}
 
 /* --- Content Area --- */
 .content-area {
@@ -1238,6 +1268,20 @@ select {
   color: var(--text-secondary);
   line-height: 1.5;
 }
+.search-result-snippet .search-highlight {
+  background: color-mix(in srgb, var(--accent) 25%, transparent);
+  color: var(--accent);
+  font-weight: 600;
+  padding: 1px 3px;
+  border-radius: 3px;
+}
+.search-result-title .search-highlight {
+  background: color-mix(in srgb, var(--accent) 25%, transparent);
+  color: var(--accent);
+  font-weight: 700;
+  padding: 1px 3px;
+  border-radius: 3px;
+}
 .search-result-tags {
   margin-top: 6px;
   display: flex;
@@ -1758,6 +1802,10 @@ body.resizing-v {
   .hamburger-btn {
     display: flex;
   }
+  
+  .sidebar-toggle-btn {
+    display: none;
+  }
 
   .header {
     gap: 6px;