[OpenSpec 与项目骨架]：完成实施型变更与 Python 基础骨架，包含 OpenSpec 工件、核心模型、配置边界和基础测试

src/owner_voice_pet/protocols.py

@@ -0,0 +1,78 @@
+from __future__ import annotations
+
+from collections.abc import Iterable, Sequence
+from typing import Protocol
+
+from .models import (
+    AudioFrame,
+    AudioSegment,
+    Message,
+    PlaybackResult,
+    ReplyDelta,
+    Transcript,
+    TransportHealth,
+    VadResult,
+    WakeEvent,
+)
+
+
+class AudioTransport(Protocol):
+    def start_input(
+        self, device_id: str | None = None, sample_rate: int = 16000, channels: int = 1
+    ) -> None:
+        ...
+
+    def read_frames(self, timeout_ms: int) -> list[AudioFrame]:
+        ...
+
+    def play_pcm(self, segment: AudioSegment, interrupt: bool = False) -> PlaybackResult:
+        ...
+
+    def stop(self) -> None:
+        ...
+
+    def health(self) -> TransportHealth:
+        ...
+
+
+class WakeWordProvider(Protocol):
+    def load(self) -> None:
+        ...
+
+    def detect(self, frame: AudioFrame) -> WakeEvent | None:
+        ...
+
+    def reset(self) -> None:
+        ...
+
+
+class VadProvider(Protocol):
+    def load(self) -> None:
+        ...
+
+    def analyze(self, frame: AudioFrame) -> VadResult:
+        ...
+
+    def reset(self) -> None:
+        ...
+
+
+class SttProvider(Protocol):
+    def load(self) -> None:
+        ...
+
+    def transcribe(self, segment: AudioSegment) -> Transcript:
+        ...
+
+
+class LlmProvider(Protocol):
+    def stream_reply(self, messages: Sequence[Message]) -> Iterable[ReplyDelta]:
+        ...
+
+
+class TtsProvider(Protocol):
+    def load(self) -> None:
+        ...
+
+    def synthesize(self, text: str) -> AudioSegment:
+        ...