Update documentation for new features and auth improvements

Expanded documentation to cover the new downloads manager, native context menu, OAuth/SSO and WebAuthn compatibility, and user agent strategy. Updated project structure and core concepts to reflect these features and clarified session and popup handling for authentication. Fixed minor typos and improved feature descriptions for clarity.

documentation/FEATURES.md

@@ -32,6 +32,15 @@ Nebula keeps a record of your browsing and search history to help you find your
 -   **Search History:** A list of all the searches you have made.
 -   **Clear History:** You can clear your history at any time from the settings page.
 
+### Downloads Manager
+
+Reliably download files with progress and controls.
+
+-   **Progress & State:** Each download shows received/total bytes and status.
+-   **Pause/Resume/Cancel:** Control active downloads where the server supports resuming.
+-   **Open or Reveal:** Open downloaded files directly or show them in your file manager.
+-   **Safe Filenames:** Files are saved to your OS Downloads folder with automatic de-duplication.
+
 ### Performance Monitoring
 
 Nebula includes built-in tools to help you monitor the browser's performance.
@@ -46,6 +55,22 @@ For advanced users, Nebula provides tools to manage GPU acceleration.
 -   **GPU Diagnostics:** View detailed information about your system's GPU and its status.
 -   **GPU Fallback:** If you experience rendering issues, you can apply a GPU fallback to use a more stable rendering path. This can help resolve visual glitches or crashes.
 
+### Native Context Menu
+
+Nebula provides a native right-click menu across pages and webviews.
+
+-   **Navigation:** Back, Forward, Reload.
+-   **Links:** Open in new tab, Download link, Open externally, Copy address.
+-   **Images:** Open in new tab, Save image as, Copy image address.
+-   **Editing:** Undo/Redo, Cut/Copy/Paste, Select All when applicable.
+-   **Developer:** Inspect Element (opens DevTools docked by default).
+
+### Authentication & Web Compatibility
+
+-   **OAuth/SSO Friendly:** Popup windows are allowed for http/https to support common login flows.
+-   **WebAuthn Diagnostics:** Platform authenticator features are enabled where supported and logged for troubleshooting.
+-   **Sturdy Navigation:** Login POST navigations are not intercepted by the main process.
+
 ### Custom Themes & Customization
 
 Nebula offers extensive customization options to personalize your browsing experience.
@@ -64,3 +89,8 @@ For detailed information about creating and managing themes, see the [Customizat
 Nebula is built with Electron, allowing it to run on multiple operating systems.
 
 -   **Windows, macOS, and Linux:** Enjoy a consistent browsing experience across different platforms.
+
+### Miscellaneous
+
+-   **User Agent Strategy:** Electron token is removed from the default user agent to improve site compatibility while appending a `Nebula/x.y.z` marker. You can opt-in to include the Electron token by setting `NEBULA_DEBUG_ELECTRON_UA=1`.
+-   **Open Local Files:** Use the file picker to open `file://` URLs directly.