Ei protocol support

- Use the configured keyboard layout, track ei seats to reconfigure their keyboards
- DBus interface
- Disambiguate input devices per backend instance
- Add support for `ei_keysym` and `ei_text`
- Act as input method for ei_text UTF-8 injection
- Create a region per output for abosolute pointer position
- Map ei region for touchscreen emulation
- Release pointer buttons and keys on removal
- Send modifiers to EI connections

src/wayland/handlers/output_configuration.rs

@@ -230,6 +230,16 @@ impl State {
             state.common.output_configuration_state.update();
         });
 
+        // Output scale or geometry may have changed. EI absolute-pointer regions
+        // are immutable per device, so any connected EI client (e.g. an RDP server)
+        // keeps mapping with the old scale until it reconnects. Recreate the
+        // device with the updated region so the mapping tracks the change live.
+        // (drop the backend lock first: refresh borrows `self` immutably.)
+        drop(backend);
+        if !test_only {
+            crate::libei::refresh_absolute_pointer_regions(self);
+        }
+
         true
     }
 }