feat(reader): wire up TOC, bookmarks, and navigator panels with Alpine.js bindings

Replace dead data-action attributes with Alpine.js @click handlers and
x-ref references across all reader panels:

- TOC panel: replaced static <nav> with x-for loop over tocItems array,
  added goToTOCItem() click handler, window-shade toggle via .tocPanel
- Bookmarks panel: replaced data-action with @click.prevent handlers,
  added goToBookmarkTarget() using data-cfi attributes for navigation,
  window-shade toggle via .bookmarksPanel
- Navigator panel: replaced data-action with @click window-shade toggle
  via .navigatorPanel
- Added goToBookmarkTarget() and toggleWindowShade() methods to reader.ts
- Removed unused panel-lock buttons (lock feature not yet implemented)
- Regenerated reader_templ.go, rebuilt CSS and JS bundles

web/static/input.css

@@ -357,4 +357,45 @@
   #collections-container[data-wood] .book-card {
     border: 1px solid var(--wood-border);
   }
+
+  .reader-icon {
+    display: block;
+    fill: none;
+    stroke: currentColor;
+    stroke-width: 2px;
+    stroke-linecap: round;
+    stroke-linejoin: round;
+  }
+
+  .dockable-panel {
+    background-color: var(--bg-secondary);
+    border-bottom: 1px solid var(--border);
+    transition: max-height 0.2s ease-out;
+    overflow: hidden;
+  }
+
+  .dockable-panel.panel-collapsed .panel-content {
+    display: none;
+  }
+
+  .panel-header {
+    user-select: none;
+  }
+
+  .panel-header:hover {
+    background-color: color-mix(in srgb, var(--bg-secondary) 90%, white);
+  }
+
+  .panel-container {
+    background-color: var(--bg-secondary);
+    border-right: 1px solid var(--border);
+    width: 320px;
+    max-height: calc(100vh - 8rem);
+    overflow-y: auto;
+  }
+
+  .panel-container[data-side="right"] {
+    border-right: none;
+    border-left: 1px solid var(--border);
+  }
 }