feat: implement OpenAI-compatible Realtime API with authentication and management features

- Added support for public Realtime API, including new routes for managing API keys and handling WebRTC connections.
- Introduced RealtimeApiKey model and associated CRUD operations for admin management of API keys.
- Implemented authentication mechanisms for API keys and client secrets.
- Enhanced environment configuration with new secrets for Realtime API.
- Created OpenAIRealtime session management and event processing for real-time interactions.
- Updated schemas and settings to accommodate new features and ensure compatibility with existing systems.

backend/services/realtime/protocol.py

@@ -0,0 +1,42 @@
+"""Neutral extension point between a transport protocol and the voice pipeline."""
+
+from __future__ import annotations
+
+from collections.abc import Awaitable, Callable
+from dataclasses import dataclass
+from typing import Literal, Protocol
+
+from pipecat.frames.frames import Frame, SystemFrame
+from pipecat.processors.frame_processor import FrameProcessor
+
+
+@dataclass(frozen=True)
+class PipelineProtocolRuntime:
+    """Operations a wire-protocol adapter may request from a running pipeline."""
+
+    queue_frame: Callable[[Frame], Awaitable[None]]
+    set_external_turn_control: Callable[[bool], Awaitable[None]]
+    set_response_interruption: Callable[[bool], Awaitable[None]]
+    commit_audio: Callable[[], Awaitable[None]]
+    clear_audio: Callable[[], Awaitable[None]]
+    request_response: Callable[[], Awaitable[None]]
+    cancel_response: Callable[[], Awaitable[None]]
+
+
+@dataclass
+class RealtimeProviderControlFrame(SystemFrame):
+    """Ordered control sent to a speech-to-speech provider after prior input."""
+
+    action: Literal["commit_audio", "clear_audio", "request_response"]
+
+
+class PipelineProtocolAdapter(Protocol):
+    """A protocol adapter only translates frames; it does not own the assistant."""
+
+    def input_processors(self) -> list[FrameProcessor]: ...
+
+    def inference_processors(self) -> list[FrameProcessor]: ...
+
+    def output_processors(self) -> list[FrameProcessor]: ...
+
+    async def bind(self, runtime: PipelineProtocolRuntime) -> None: ...