Fix main-thread blocking I/O

Library/Database/Profile+RW.swift

@@ -2,6 +2,9 @@ import Foundation
 
 public extension Profile {
     func read() throws -> String {
+        #if DEBUG
+            precondition(!Thread.isMainThread, "Profile.read() must not be called on the main thread")
+        #endif
         switch type {
         case .local, .remote:
             return try String(contentsOfFile: path)
@@ -12,6 +15,9 @@ public extension Profile {
     }
 
     func write(_ content: String) throws {
+        #if DEBUG
+            precondition(!Thread.isMainThread, "Profile.write(...) must not be called on the main thread")
+        #endif
         switch type {
         case .local, .remote:
             try content.write(toFile: path, atomically: true, encoding: .utf8)
@@ -20,4 +26,33 @@ public extension Profile {
             try content.write(to: saveURL, atomically: true, encoding: .utf8)
         }
     }
+
+    func readAsync() async throws -> String {
+        let type = type
+        let path = path
+        return try await BlockingIO.run {
+            switch type {
+            case .local, .remote:
+                return try String(contentsOfFile: path)
+            case .icloud:
+                let saveURL = FilePath.iCloudDirectory.appendingPathComponent(path)
+                return try String(contentsOf: saveURL)
+            }
+        }
+    }
+
+    func writeAsync(_ content: String) async throws {
+        let type = type
+        let path = path
+        let content = content
+        try await BlockingIO.run {
+            switch type {
+            case .local, .remote:
+                try content.write(toFile: path, atomically: true, encoding: .utf8)
+            case .icloud:
+                let saveURL = FilePath.iCloudDirectory.appendingPathComponent(path)
+                try content.write(to: saveURL, atomically: true, encoding: .utf8)
+            }
+        }
+    }
 }