refactor: Remove unused swift-perception dependency, target macOS 15+ only

Package.swift

@@ -5,10 +5,7 @@ import PackageDescription
 let package = Package(
   name: "sqlite-data",
   platforms: [
-    .iOS(.v13),
-    .macOS(.v10_15),
-    .tvOS(.v13),
-    .watchOS(.v7),
+    .macOS(.v15),
   ],
   products: [
     .library(

Package@swift-6.0.swift

@@ -5,10 +5,7 @@ import PackageDescription
 let package = Package(
   name: "sqlite-data",
   platforms: [
-    .iOS(.v13),
-    .macOS(.v10_15),
-    .tvOS(.v13),
-    .watchOS(.v7),
+    .macOS(.v15),
   ],
   products: [
     .library(

Sources/SQLiteData/FetchSubscription.swift

@@ -0,0 +1,46 @@
+import ConcurrencyExtras
+import Sharing
+
+/// A subscription associated with `@FetchAll`, `@FetchOne`, and `@Fetch` observation.
+///
+/// This value can be useful in associating the lifetime of observing a query to the lifetime of a
+/// SwiftUI view _via_ the `task` view modifier. For example, loading a query in a view's `task`
+/// will automatically cancel the observation when drilling down into a child view, and restart
+/// observation when popping back to the view:
+///
+/// ```swift
+/// .task {
+///   try? await $reminders.load(Reminder.all).task
+/// }
+/// ```
+public struct FetchSubscription: Sendable {
+  let cancellable = LockIsolated<Task<Void, any Error>?>(nil)
+  let onCancel: @Sendable () -> Void
+
+  init<Value>(sharedReader: SharedReader<Value>) {
+    onCancel = { sharedReader.projectedValue = SharedReader(value: sharedReader.wrappedValue) }
+  }
+
+  /// An async handle to the given fetch observation.
+  ///
+  /// This handle will suspend until the current task is cancelled, at which point it will terminate
+  /// the observation of the associated ``FetchAll``, ``FetchOne``, or ``Fetch``.
+  public var task: Void {
+    get async throws {
+      let task = Task {
+        try await withTaskCancellationHandler {
+          try await Task.never()
+        } onCancel: {
+          onCancel()
+        }
+      }
+      cancellable.withValue { $0 = task }
+      try await task.cancellableValue
+    }
+  }
+
+  /// Cancels the database observation of the associated ``FetchAll``, ``FetchOne``, or ``Fetch``.
+  public func cancel() {
+    cancellable.value?.cancel()
+  }
+}