feat: Adds generate-config as json file.

Sources/CliClient/FileClient.swift

@@ -18,6 +18,7 @@ public struct FileClient: Sendable {
   public var homeDir: @Sendable () -> URL = { URL(string: "~/")! }
   public var isDirectory: @Sendable (URL) -> Bool = { _ in false }
   public var isReadable: @Sendable (URL) -> Bool = { _ in false }
+  public var fileExists: @Sendable (String) -> Bool = { _ in false }
   public var write: @Sendable (String, Data) throws -> Void
 }
 
@@ -33,6 +34,7 @@ extension FileClient: DependencyKey {
       homeDir: { client.homeDir },
       isDirectory: { client.isDirectory(url: $0) },
       isReadable: { client.isReadable(url: $0) },
+      fileExists: { client.fileExists(at: $0) },
       write: { path, data in
         try data.write(to: URL(filePath: path))
       }
@@ -66,6 +68,10 @@ private struct LiveFileClient: @unchecked Sendable {
     try fileManager.contentsOfDirectory(at: url, includingPropertiesForKeys: nil)
   }
 
+  func fileExists(at path: String) -> Bool {
+    fileManager.fileExists(atPath: path)
+  }
+
   func loadFile(at url: URL, into env: inout [String: String], decoder: JSONDecoder) throws {
     @Dependency(\.logger) var logger
     logger.trace("Begin load file for: \(path(for: url))")