feat: add provider interface and registry

internal/provider/elevenlabs.go

@@ -0,0 +1,41 @@
+package provider
+
+// ElevenLabsProvider implements Provider for ElevenLabs services (transcription only)
+type ElevenLabsProvider struct{}
+
+func (p *ElevenLabsProvider) Name() string {
+	return "elevenlabs"
+}
+
+func (p *ElevenLabsProvider) RequiresAPIKey() bool {
+	return true
+}
+
+func (p *ElevenLabsProvider) ValidateAPIKey(key string) bool {
+	// ElevenLabs API keys don't have a consistent prefix, just check non-empty
+	return len(key) > 0
+}
+
+func (p *ElevenLabsProvider) SupportsTranscription() bool {
+	return true
+}
+
+func (p *ElevenLabsProvider) SupportsLLM() bool {
+	return false
+}
+
+func (p *ElevenLabsProvider) DefaultTranscriptionModel() string {
+	return "scribe_v1"
+}
+
+func (p *ElevenLabsProvider) DefaultLLMModel() string {
+	return ""
+}
+
+func (p *ElevenLabsProvider) TranscriptionModels() []string {
+	return []string{"scribe_v1", "scribe_v2"}
+}
+
+func (p *ElevenLabsProvider) LLMModels() []string {
+	return nil
+}