feat: controller supports vocabulary bias, prompt-echo guard, corrector and result hook

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

Tests/SstCoreTests/Fakes.swift

@@ -41,3 +41,31 @@ final class FakeInserter: TextInserting {
         inserted.append(text)
     }
 }
+
+final class FakeVocabularyTranscriber: Transcriber {
+    var result = "hallo wereld"
+    private(set) var vocabularies: [[String]] = []
+
+    func transcribe(_ samples: [Float]) async throws -> String { result }
+
+    func transcribe(_ samples: [Float], vocabulary: [String]) async throws -> String {
+        vocabularies.append(vocabulary)
+        return result
+    }
+}
+
+struct UppercaseCorrector: TextCorrecting {
+    func correct(_ text: String) -> CorrectionResult {
+        let upper = text.uppercased()
+        return CorrectionResult(
+            text: upper,
+            corrections: [AppliedCorrection(heard: text, wrote: upper, rule: "upper", start: 0, length: upper.utf16.count)]
+        )
+    }
+}
+
+final class PassthroughCleaner: Cleaner {
+    func clean(_ text: String, context: CleaningContext) async throws -> String {
+        text
+    }
+}