Add audio generation config, refactor rep_announcer

- AudioConfig now includes rep_max_count and rep_audio_dir
- app/audio/generate.py uses config instead of hardcoded constants
- RepAnnouncer rewrote with pre-generated audio cache
- Supports Windows winsound, macOS afplay, Linux paplay/aplay
- Pin requirements back to mediapipe==0.10.21 with numpy<2

app/audio/generate.py

@@ -0,0 +1,124 @@
+# app/audio/generate.py
+from __future__ import annotations
+
+import platform
+import shutil
+import subprocess
+from pathlib import Path
+
+from loguru import logger
+
+
+def generate_rep_audio_files(
+    *,
+    max_count: int,
+    rate: int,
+    output_dir: Path,
+    overwrite: bool = False,
+) -> None:
+    """
+    确保 0~max_count 的运动次数语音 wav 文件存在。
+
+    默认生成到：
+
+        app/audio/reps/0.wav
+        app/audio/reps/1.wav
+        ...
+        app/audio/reps/200.wav
+
+    服务启动时调用一次即可。
+    """
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    missing_counts = [
+        count
+        for count in range(0, max_count + 1)
+        if overwrite or not _audio_path(output_dir, count).exists()
+    ]
+
+    if not missing_counts:
+        logger.info("Rep audio files already prepared: {}", output_dir)
+        return
+
+    system = platform.system().lower()
+
+    logger.info(
+        "Preparing rep audio files, system={}, count={}, output_dir={}",
+        system,
+        len(missing_counts),
+        output_dir,
+    )
+
+    if system == "darwin":
+        _generate_with_macos_say(
+            counts=missing_counts,
+            output_dir=output_dir,
+            rate=rate,
+        )
+    else:
+        _generate_with_pyttsx3(
+            counts=missing_counts,
+            output_dir=output_dir,
+            rate=rate,
+        )
+
+    logger.info("Rep audio files prepared: {}", output_dir)
+
+
+def _generate_with_macos_say(
+    *,
+    counts: list[int],
+    output_dir: Path,
+    rate: int,
+) -> None:
+    """macOS 使用 say 命令生成 wav。"""
+    if platform.system().lower() != "darwin":
+        raise RuntimeError("say command is only available on macOS")
+
+    if shutil.which("say") is None:
+        raise RuntimeError("macOS say command not found")
+
+    for count in counts:
+        audio_file = _audio_path(output_dir, count)
+
+        subprocess.run(
+            [
+                "say",
+                "-r",
+                str(rate),
+                "--file-format=WAVE",
+                "-o",
+                str(audio_file),
+                str(count),
+            ],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+            check=True,
+        )
+
+
+def _generate_with_pyttsx3(
+    *,
+    counts: list[int],
+    output_dir: Path,
+    rate: int,
+) -> None:
+    """Windows / Linux 使用 pyttsx3 生成 wav。"""
+    try:
+        import pyttsx3
+    except Exception as exc:
+        raise RuntimeError(f"pyttsx3 unavailable: {exc}") from exc
+
+    engine = pyttsx3.init()
+    engine.setProperty("rate", rate)
+    engine.setProperty("volume", 1.0)
+
+    for count in counts:
+        audio_file = _audio_path(output_dir, count)
+        engine.save_to_file(str(count), str(audio_file))
+
+    engine.runAndWait()
+
+
+def _audio_path(output_dir: Path, count: int) -> Path:
+    return output_dir / f"{count}.wav"