add simple transcription with adapters

internal/transcriber/adapter_whispercpp.go

@@ -0,0 +1,31 @@
+package transcriber
+
+import (
+	"context"
+	"fmt"
+)
+
+// WhisperCppAdapter implements TranscriptionAdapter for local whisper.cpp
+type WhisperCppAdapter struct {
+	config    Config
+	modelPath string
+}
+
+func NewWhisperCppAdapter(config Config) *WhisperCppAdapter {
+	return &WhisperCppAdapter{
+		config: config,
+		// TODO: Configure model path based on config
+		modelPath: "./models/ggml-base.en.bin",
+	}
+}
+
+func (a *WhisperCppAdapter) Transcribe(ctx context.Context, audioData []byte) (string, error) {
+	// TODO: Implement whisper.cpp transcription
+	// This will involve:
+	// 1. Writing audio data to a temporary file or pipe
+	// 2. Calling whisper.cpp binary with appropriate flags
+	// 3. Reading the transcription result
+	// 4. Cleaning up temporary files
+
+	return "", fmt.Errorf("whisper.cpp adapter not implemented yet")
+}