Implement DashScope ASR provider and enhance ASR service architecture

- Added DashScope ASR service implementation for real-time streaming.
- Updated ASR provider logic to support DashScope alongside existing providers.
- Enhanced runtime metadata resolution to include DashScope as a valid ASR provider.
- Modified configuration files and documentation to reflect the addition of DashScope.
- Introduced tests to validate DashScope integration and ASR service behavior.
- Refactored ASR service factory to accommodate new provider options and modes.

engine/docs/extension_ports.md

@@ -20,7 +20,7 @@ This document defines the draft port set used to keep core runtime extensible.
 - `runtime/ports/asr.py`
   - `ASRServiceSpec`
   - `ASRPort`
-  - optional extensions: `ASRInterimControl`, `ASRBufferControl`
+  - explicit mode ports: `OfflineASRPort`, `StreamingASRPort`
 - `runtime/ports/service_factory.py`
   - `RealtimeServiceFactory`
 
@@ -39,7 +39,7 @@ This document defines the draft port set used to keep core runtime extensible.
   - supported providers: `dashscope`, `openai_compatible`, `openai-compatible`, `siliconflow`
   - fallback: `MockTTSService`
 - ASR:
-  - supported providers: `openai_compatible`, `openai-compatible`, `siliconflow`
+  - supported providers: `openai_compatible`, `openai-compatible`, `siliconflow`, `dashscope`
   - fallback: `BufferedASRService`
 
 ## Notes