Design a fully professional Android App Manager application using Sketchware Pro that strictly follows Material 3 (Material You) principles, but implement everything using Fully Java code and Fully XML layouts. No extra assets or libraries.

Requirement:
- App must list installed applications, divided into Downloaded Apps and System Apps.

Application Structure:

1️⃣ Main Screen (MainActivity.java + activity_main.xml):
- Top ActionBar (Toolbar style simulated):
• Title: App Manager
• Right-side icons:
- Search Icon → Opens SearchActivity
- Refresh Icon → Reload apps
- 3-dot Overflow Menu:
- Settings → Opens SettingsActivity
- Developer Info → Opens DeveloperActivity
• Build using a horizontal LinearLayout with TextView (for title) and ImageViews (for icons), inside a CardView or elevated LinearLayout to simulate Material 3 TopAppBar.

- Tab Layout:
• 2 Tabs: "Downloaded Apps" and "System Apps".
• Use horizontal LinearLayout with two TextViews styled as tabs.
• Selected tab text color: #000000 (Black).
• Unselected tab text color: #888888 (Grey).
• Use a View (height=2dp) below active tab as indicator with dynamic accent color.

- App List:
• Use ListView (or CustomListView) to display installed apps.
• Each item must be a CardView-style LinearLayout in a custom item_app.xml:
- ImageView: App Icon (Rounded)
- TextView: App Name (Bold)
- TextView: Package Name (Small)
• OnClick: Open AppDetailsActivity passing the package name.

- Loading Indicator:
• Use ProgressBar (Circular) with dynamic colors.
• Show/hide using View.VISIBLE and View.GONE during app loading.

- Empty State:
• If no apps found, show centered ImageView (placeholder image) and TextView with text "No apps found".

2️⃣ App Details Screen (AppDetailsActivity.java + activity_app_details.xml):
- TopAppBar (Same structure):
• Back Arrow Icon (ImageView)
• App Name (Centered Title)
• 3-dot Overflow Menu:
- Find in Market
- Backup APK

- Main Layout:
• App Icon (Large ImageView)
• App Name (TextView)

- Main Buttons (use Buttons in XML):
• Launch App (Filled Button)
• Uninstall (Outlined Button)
• App Settings (Text Button)

- App Information List:
• Display app details like:
- Package Name
- Version
- Installed Date
- App Size
- APK Path
- Permissions List
- Target SDK / Min SDK
• Use LinearLayouts inside a ScrollView for scrolling content.

3️⃣ Settings Screen (SettingsActivity.java + activity_settings.xml):
- Light, Dark, System Default Theme Selection
- Switch to toggle Dynamic Color
- Dropdown to select Sorting: A-Z, Size, Installed Date
- About Section with app info

4️⃣ Developer Info Screen (DeveloperActivity.java + activity_developer.xml):
- Static Information about developer.

UI Design Notes:
- Use #FFFFFF as background color throughout.
- Use dynamic accent colors for active tabs, indicators, buttons.
- Use Rounded Corners (16dp) for all Cards, Buttons, App Icons.
- Use Material Symbols Rounded icons (as PNG drawables).
- Add soft shadows using CardView or elevation.
- Ensure proper padding (16dp standard) around all UI elements.
- Use animations between activities (slide in/out) using Java.

General Implementation:
- Use Fully Java code to handle all app loading, click events, list population, APK backup, uninstall intents, open in Play Store, app settings, etc.
- Layouts must be built using Fully XML code with no dependency on Sketchware's GUI editor.
- No external libraries allowed; use standard Sketchware Pro components and native Android methods.

Output must result in a clean, modern, dynamic Material 3-like App Manager experience inside Sketchware Pro.

1. Download & read PDFs from any URL
2. Offline caching for reading anytime
3. Live download progress with retry option
4. Vertical & horizontal scroll modes
5. Night & day mode toggle
6. Go-to page functionality
7. Last page memory
8. Auto-hide toolbar in vertical mode
9. Double-tap zoom & annotation support
10. Clean modern UI with transparent system bars
11. Robust handling for network & interruptions