Refactor VoiceAgent: Extract types and default configurations into separate types.ts file; remove unused StreamBuffer file

src/index.ts

@@ -1 +1,22 @@
+// Agents
 export { VoiceAgent, type VoiceAgentOptions } from "./VoiceAgent";
+export {
+    VideoAgent,
+    type VideoAgentOptions,
+    type VideoFrame,
+    type AudioData,
+    type VideoAgentConfig,
+    type FrameContext,
+    type FrameTriggerReason,
+} from "./VideoAgent";
+
+// Shared types
+export {
+    type SpeechChunk,
+    type StreamingSpeechConfig,
+    type HistoryConfig,
+    type StopWhenCondition,
+    DEFAULT_STREAMING_SPEECH_CONFIG,
+    DEFAULT_HISTORY_CONFIG,
+    DEFAULT_MAX_AUDIO_SIZE,
+} from "./types";