Refactor project structure and enhance backend integration

- Expanded package inclusion in `pyproject.toml` to support new modules.
- Introduced new `adapters` and `protocol` packages for better organization.
- Added backend adapter implementations for control plane integration.
- Updated main application imports to reflect new package structure.
- Removed deprecated core components and adjusted documentation accordingly.
- Enhanced architecture documentation to clarify the new runtime and integration layers.

engine/runtime/ports/service_factory.py

@@ -0,0 +1,22 @@
+"""Factory port for creating runtime ASR/LLM/TTS services."""
+
+from __future__ import annotations
+
+from typing import Protocol
+
+from runtime.ports.asr import ASRPort, ASRServiceSpec
+from runtime.ports.llm import LLMPort, LLMServiceSpec
+from runtime.ports.tts import TTSPort, TTSServiceSpec
+
+
+class RealtimeServiceFactory(Protocol):
+    """Port for provider-specific service construction."""
+
+    def create_llm_service(self, spec: LLMServiceSpec) -> LLMPort:
+        """Create an LLM service instance from a resolved spec."""
+
+    def create_tts_service(self, spec: TTSServiceSpec) -> TTSPort:
+        """Create a TTS service instance from a resolved spec."""
+
+    def create_asr_service(self, spec: ASRServiceSpec) -> ASRPort:
+        """Create an ASR service instance from a resolved spec."""