Fix issues with CK{Record,Share}.SystemFieldsRepresentation (#284)

* Fix issues with `CK{Record,Share}.SystemFieldsRepresentation`

I'm a little surprised that this diff fixes things, but it does locally
for me, in the latest Xcode 26, so let's test this change a bit before
merging.

* Compile time tests

* wip;

* wip

---------

Co-authored-by: Brandon Williams <[email protected]>

Author: stephencelis

Sources/SQLiteData/CloudKit/CloudKit+StructuredQueries.swift

@@ -3,12 +3,12 @@
   import CryptoKit
   import StructuredQueriesCore
 
-  extension _CKRecord where Self == CKRecord {
+  extension CKRecord {
     public typealias _AllFieldsRepresentation = SQLiteData._AllFieldsRepresentation<CKRecord>
     public typealias SystemFieldsRepresentation = _SystemFieldsRepresentation<CKRecord>
   }
 
-  extension _CKRecord where Self == CKShare {
+  extension CKShare {
     public typealias _AllFieldsRepresentation = SQLiteData._AllFieldsRepresentation<CKShare>
     public typealias SystemFieldsRepresentation = _SystemFieldsRepresentation<CKShare>
   }
@@ -102,10 +102,6 @@
     private struct DecodingError: Error {}
   }
 
-  extension CKRecord: _CKRecord {}
-
-  public protocol _CKRecord {}
-
   extension CKDatabase.Scope {
     public struct RawValueRepresentation: QueryBindable, QueryRepresentable {
       public let queryOutput: CKDatabase.Scope

Tests/SQLiteDataTests/CompileTimeTests.swift

@@ -1,9 +1,43 @@
 import SQLiteData
 
+#if canImport(CloudKit)
+  import CloudKit
+#endif
+
 private final class Model {
   @FetchAll var titles: [String]
 
   init() {
     _titles = FetchAll(Reminder.select(\.title))
   }
 }
+
+#if canImport(CloudKit)
+  @Table
+  struct RepresentableFields {
+    @Column(as: CKShare.SystemFieldsRepresentation.self)
+    var share: CKShare
+    @Column(as: CKShare?.SystemFieldsRepresentation.self)
+    var optionalShare: CKShare?
+    @Column(as: CKRecord.SystemFieldsRepresentation.self)
+    var record: CKRecord
+    @Column(as: CKRecord?.SystemFieldsRepresentation.self)
+    var optionalRecord: CKRecord?
+  }
+
+  @DatabaseFunction(
+    as: ((
+      CKShare.SystemFieldsRepresentation,
+      CKRecord.SystemFieldsRepresentation,
+      CKShare?.SystemFieldsRepresentation,
+      CKRecord?.SystemFieldsRepresentation
+    ) -> Void).self
+  )
+  nonisolated func representableArguments(
+    share: CKShare,
+    record: CKRecord,
+    optionalShare: CKShare?,
+    optionalRecord: CKRecord?
+  ) {
+  }
+#endif