reader: convert feature modules to Feature Registration Pattern

- Add init(context) exported function to each feature module
- Store module-level context reference for event handlers
- Fix gestures.ts to use library_type_name instead of library_type
- Features: gestures, keyboard-shortcuts, navigator-panel, offline-manager,
  panel-dock-system, progress-indicator, reading-speed-tracker

web/src/reader/features/navigator-panel.ts

@@ -4,23 +4,32 @@
 
 import type { ReaderContext } from "../core/reader-context";
 
-export function init(context: ReaderContext): void {
+let context: ReaderContext;
+
+export function init(readerContext: ReaderContext): void {
+  context = readerContext;
   let state: NavigatorState | null = null;
 
-  context.events.on("navigator:initialize", (detail: { containerSelector: string; totalPages: number }) => {
-    state = initializeNavigator(detail.containerSelector);
-    state.totalPages = detail.totalPages;
-  });
+  context.events.on(
+    "navigator:initialize",
+    (detail: { containerSelector: string; totalPages: number }) => {
+      state = initializeNavigator(detail.containerSelector);
+      state.totalPages = detail.totalPages;
+    },
+  );
 
-  context.events.on("navigator:update", (detail: { currentPage: number; contentImage?: HTMLImageElement }) => {
-    if (state) {
-      state.currentPage = detail.currentPage;
-      if (detail.contentImage) {
-        state.contentImage = detail.contentImage;
-        updateNavigatorViewport(state);
+  context.events.on(
+    "navigator:update",
+    (detail: { currentPage: number; contentImage?: HTMLImageElement }) => {
+      if (state) {
+        state.currentPage = detail.currentPage;
+        if (detail.contentImage) {
+          state.contentImage = detail.contentImage;
+          updateNavigatorViewport(state);
+        }
       }
-    }
-  });
+    },
+  );
 
   context.events.on("navigator:pan", (detail: { x: number; y: number }) => {
     if (state) {
@@ -124,10 +133,10 @@ function handleNavigatorPan(state: NavigatorState, x: number, y: number): void {
   if (!state.contentImage) return;
 
   const imgRect = state.contentImage.getBoundingClientRect();
-  
+
   const viewportX = x * state.container.offsetWidth;
   const viewportY = y * state.container.offsetHeight;
 
   state.viewport.style.left = `${viewportX}px`;
   state.viewport.style.top = `${viewportY}px`;
-}
+}