feat: add package scaffold and DictationController state machine

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Tests/SstCoreTests/Fakes.swift

@@ -0,0 +1,43 @@
+import Foundation
+@testable import SstCore
+
+struct TestError: Error {}
+
+final class FakeRecorder: AudioRecording {
+    var samples: [Float] = []
+    var startError: Error?
+    private(set) var startCount = 0
+
+    func start() throws {
+        startCount += 1
+        if let startError { throw startError }
+    }
+
+    func stop() -> [Float] { samples }
+}
+
+final class FakeTranscriber: Transcriber {
+    var result: Result<String, Error> = .success("hallo wereld")
+    private(set) var callCount = 0
+
+    func transcribe(_ samples: [Float]) async throws -> String {
+        callCount += 1
+        return try result.get()
+    }
+}
+
+final class FakeCleaner: Cleaner {
+    func clean(_ text: String, context: CleaningContext) async throws -> String {
+        "[\(text)]"
+    }
+}
+
+final class FakeInserter: TextInserting {
+    var error: Error?
+    private(set) var inserted: [String] = []
+
+    func insert(_ text: String) async throws {
+        if let error { throw error }
+        inserted.append(text)
+    }
+}