feat: add Groq Whisper API support for transcription and translation

Add support for Groq Whisper API as an alternative to OpenAI:
- groq-transcription: Fast transcription using whisper-large-v3 or whisper-large-v3-turbo
- groq-translation: Translation to English (whisper-large-v3 only)

Features:
- New transcription adapters for both Groq services
- Config validation with provider-specific model restrictions
- API key support via config file or GROQ_API_KEY environment variable
- Updated interactive configuration wizard with provider selection
- Comprehensive test coverage for all providers
- Shared WAV conversion utility for audio preprocessing

Breaking changes: None
Backward compatibility: Existing OpenAI configurations continue to work unchanged

internal/transcriber/transcriber_test.go

@@ -35,6 +35,46 @@ func TestNewTranscriber(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "valid groq-transcription config",
+			config: Config{
+				Provider: "groq-transcription",
+				APIKey:   "gsk-test-key",
+				Language: "en",
+				Model:    "whisper-large-v3",
+			},
+			wantErr: false,
+		},
+		{
+			name: "groq-transcription config without api key",
+			config: Config{
+				Provider: "groq-transcription",
+				APIKey:   "",
+				Language: "en",
+				Model:    "whisper-large-v3",
+			},
+			wantErr: true,
+		},
+		{
+			name: "valid groq-translation config",
+			config: Config{
+				Provider: "groq-translation",
+				APIKey:   "gsk-test-key",
+				Language: "es",
+				Model:    "whisper-large-v3-turbo",
+			},
+			wantErr: false,
+		},
+		{
+			name: "groq-translation config without api key",
+			config: Config{
+				Provider: "groq-translation",
+				APIKey:   "",
+				Language: "es",
+				Model:    "whisper-large-v3-turbo",
+			},
+			wantErr: true,
+		},
 		{
 			name: "unsupported provider",
 			config: Config{