Add calendar plugin constants

core/shared/src/main/java/de/mm20/launcher2/plugin/PluginType.kt

@@ -4,4 +4,5 @@ enum class PluginType {
     FileSearch,
     Weather,
     LocationSearch,
+    Calendar,
 }

core/shared/src/main/java/de/mm20/launcher2/plugin/contracts/CalendarPluginContract.kt

@@ -0,0 +1,50 @@
+package de.mm20.launcher2.plugin.contracts
+
+abstract class CalendarPluginContract {
+    object EventColumns: Columns() {
+        /**
+         * The unique ID of the event.
+         */
+        val Id = column<String>("id")
+
+        /**
+         * The title of the event.
+         */
+        val Title = column<String>("title")
+
+        /**
+         * The description of the event.
+         */
+        val Description = column<String>("description")
+
+        /**
+         * The location of the event.
+         */
+        val Location = column<String>("location")
+
+        /**
+         * The start time of the event.
+         */
+        val StartTime = column<Long>("start_time")
+
+        /**
+         * The end time of the event.
+         */
+        val EndTime = column<Long>("end_time")
+
+        /**
+         * Whether the event is an all-day event.
+         */
+        val AllDay = column<Boolean>("all_day")
+
+        /**
+         * The color of the event.
+         */
+        val Color = column<Int>("color")
+
+        /**
+         * The attendees of the event.
+         */
+        val Attendees = column<List<String>>("attendees")
+    }
+}