refactor: change browse activities to ActivityWithSubactivity

Change HomeActivity, MyLibraryActivity, and RecentBooksActivity base
class from Activity to ActivityWithSubactivity. Adds subActivity
guard at top of each loop(). No new behavior, just enabling sub-activity
hosting for the upcoming BookManageMenuActivity integration.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/activities/home/HomeActivity.cpp

@@ -124,7 +124,7 @@ void HomeActivity::loadRecentCovers(int coverHeight) {
 }
 
 void HomeActivity::onEnter() {
-  Activity::onEnter();
+  ActivityWithSubactivity::onEnter();
 
   // Check if OPDS browser URL is configured
   hasOpdsUrl = strlen(SETTINGS.opdsServerUrl) > 0;
@@ -139,7 +139,7 @@ void HomeActivity::onEnter() {
 }
 
 void HomeActivity::onExit() {
-  Activity::onExit();
+  ActivityWithSubactivity::onExit();
 
   // Free the stored cover buffer if any
   freeCoverBuffer();
@@ -188,6 +188,11 @@ void HomeActivity::freeCoverBuffer() {
 }
 
 void HomeActivity::loop() {
+  if (subActivity) {
+    subActivity->loop();
+    return;
+  }
+
   const int menuCount = getMenuItemCount();
 
   buttonNavigator.onNext([this, menuCount] {

src/activities/home/HomeActivity.h

@@ -2,14 +2,14 @@
 #include <functional>
 #include <vector>
 
-#include "../Activity.h"
+#include "../ActivityWithSubactivity.h"
 #include "./MyLibraryActivity.h"
 #include "util/ButtonNavigator.h"
 
 struct RecentBook;
 struct Rect;
 
-class HomeActivity final : public Activity {
+class HomeActivity final : public ActivityWithSubactivity {
   ButtonNavigator buttonNavigator;
   int selectorIndex = 0;
   bool recentsLoading = false;
@@ -40,7 +40,7 @@ class HomeActivity final : public Activity {
                         const std::function<void()>& onMyLibraryOpen, const std::function<void()>& onRecentsOpen,
                         const std::function<void()>& onSettingsOpen, const std::function<void()>& onFileTransferOpen,
                         const std::function<void()>& onOpdsBrowserOpen)
-      : Activity("Home", renderer, mappedInput),
+      : ActivityWithSubactivity("Home", renderer, mappedInput),
         onSelectBook(onSelectBook),
         onMyLibraryOpen(onMyLibraryOpen),
         onRecentsOpen(onRecentsOpen),

src/activities/home/MyLibraryActivity.cpp

@@ -103,7 +103,7 @@ void MyLibraryActivity::loadFiles() {
 }
 
 void MyLibraryActivity::onEnter() {
-  Activity::onEnter();
+  ActivityWithSubactivity::onEnter();
 
   loadFiles();
   selectorIndex = 0;
@@ -112,11 +112,16 @@ void MyLibraryActivity::onEnter() {
 }
 
 void MyLibraryActivity::onExit() {
-  Activity::onExit();
+  ActivityWithSubactivity::onExit();
   files.clear();
 }
 
 void MyLibraryActivity::loop() {
+  if (subActivity) {
+    subActivity->loop();
+    return;
+  }
+
   // Long press BACK (1s+) goes to root folder
   if (mappedInput.isPressed(MappedInputManager::Button::Back) && mappedInput.getHeldTime() >= GO_HOME_MS &&
       basepath != "/") {

src/activities/home/MyLibraryActivity.h

@@ -3,11 +3,11 @@
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
+#include "../ActivityWithSubactivity.h"
 #include "RecentBooksStore.h"
 #include "util/ButtonNavigator.h"
 
-class MyLibraryActivity final : public Activity {
+class MyLibraryActivity final : public ActivityWithSubactivity {
  private:
   ButtonNavigator buttonNavigator;
 
@@ -30,7 +30,7 @@ class MyLibraryActivity final : public Activity {
                              const std::function<void()>& onGoHome,
                              const std::function<void(const std::string& path)>& onSelectBook,
                              std::string initialPath = "/")
-      : Activity("MyLibrary", renderer, mappedInput),
+      : ActivityWithSubactivity("MyLibrary", renderer, mappedInput),
         basepath(initialPath.empty() ? "/" : std::move(initialPath)),
         onSelectBook(onSelectBook),
         onGoHome(onGoHome) {}

src/activities/home/RecentBooksActivity.cpp

@@ -31,7 +31,7 @@ void RecentBooksActivity::loadRecentBooks() {
 }
 
 void RecentBooksActivity::onEnter() {
-  Activity::onEnter();
+  ActivityWithSubactivity::onEnter();
 
   // Load data
   loadRecentBooks();
@@ -41,11 +41,16 @@ void RecentBooksActivity::onEnter() {
 }
 
 void RecentBooksActivity::onExit() {
-  Activity::onExit();
+  ActivityWithSubactivity::onExit();
   recentBooks.clear();
 }
 
 void RecentBooksActivity::loop() {
+  if (subActivity) {
+    subActivity->loop();
+    return;
+  }
+
   const int pageItems = UITheme::getInstance().getNumberOfItemsPerPage(renderer, true, false, true, true);
 
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {

src/activities/home/RecentBooksActivity.h

@@ -5,11 +5,11 @@
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
+#include "../ActivityWithSubactivity.h"
 #include "RecentBooksStore.h"
 #include "util/ButtonNavigator.h"
 
-class RecentBooksActivity final : public Activity {
+class RecentBooksActivity final : public ActivityWithSubactivity {
  private:
   ButtonNavigator buttonNavigator;
 
@@ -29,7 +29,7 @@ class RecentBooksActivity final : public Activity {
   explicit RecentBooksActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
                                const std::function<void()>& onGoHome,
                                const std::function<void(const std::string& path)>& onSelectBook)
-      : Activity("RecentBooks", renderer, mappedInput), onSelectBook(onSelectBook), onGoHome(onGoHome) {}
+      : ActivityWithSubactivity("RecentBooks", renderer, mappedInput), onSelectBook(onSelectBook), onGoHome(onGoHome) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;