Use external library for API interface and IPC.

tmp/Enums/PenumbraApiEc.cs

@@ -0,0 +1,20 @@
+namespace Penumbra.Api.Enums;
+
+public enum PenumbraApiEc
+{
+    Success            = 0,
+    NothingChanged     = 1,
+    CollectionMissing  = 2,
+    ModMissing         = 3,
+    OptionGroupMissing = 4,
+    OptionMissing      = 5,
+
+    CharacterCollectionExists = 6,
+    LowerPriority             = 7,
+    InvalidGamePath           = 8,
+    FileMissing               = 9,
+    InvalidManipulation       = 10,
+    InvalidArgument           = 11,
+    PathRenameFailed          = 12,
+    UnknownError              = 255,
+}