Update README with Linux file drag-and-drop details

Added information about file drag-and-drop functionality on Linux with Wayland backend.

README.md

@@ -283,6 +283,20 @@ Installers and executables are code-signed.
 | Fedora/RHEL/openSUSE | `effectcraft-<ver>-linux-x86_64.rpm` | `effectcraft-<ver>-linux-aarch64.rpm` | |
 | Tarball | `effectcraft-<ver>-linux-x86_64.tar.gz` | `effectcraft-<ver>-linux-aarch64.tar.gz` | Unpack anywhere |
 
+**File drag-and-drop on Linux:** The current eframe/winit 0.30 native Wayland backend does not
+deliver file-hover or file-drop events. On Hyprland and other native Wayland sessions, use
+**File ▸ Import ▸ File…** (which accepts multiple files), or start EffectCraft via XWayland if
+XWayland is installed and `DISPLAY` is set:
+
+```sh
+env -u WAYLAND_DISPLAY effectcraft
+```
+
+When the backend delivers events (X11/XWayland, Windows and macOS), dropping media anywhere
+in the window imports it, and a drop-target hint appears while hovering. On native Wayland the
+app cannot detect an attempt that generates no event; it shows a startup notice with the
+File ▸ Import fallback instead.
+
 ### FreeBSD
 
 | Build | File |