Add invert option for covers with reversed open/close logic

- Add invert: true option in airsend.yaml for covers where
  open/close logic is reversed (e.g. shade sails, projector screens)
- UP/DOWN commands are swapped when invert is enabled
- Position value is mirrored (100 - position) for covers with position
- is_closed state logic is inverted accordingly
- inverted: true shown in entity attributes when active

custom_components/airsend/device.py

@@ -88,6 +88,10 @@ class Device:
             self._refresh = int(options["refresh"])
         except KeyError:
             pass
+        try:
+            self._invert = bool(options["invert"])
+        except KeyError:
+            self._invert = False
 
     @property
     def name(self) -> str:
@@ -158,6 +162,11 @@ class Device:
     def is_light(self) -> bool:
         return self._rtype == 4100
 
+    @property
+    def is_inverted(self) -> bool:
+        """Return True if open/close logic is inverted."""
+        return self._invert
+
     @property
     def refresh_value(self) -> int:
         """Return refresh value in seconds."""