feat: 隐藏后台面板 + /api/stats 运行统计

- 连点页脚提示 6 次唤出管理面板：本机偏好/播放状态 + 服务器统计
- server.py 新增 GET /api/stats：运行时长、访客 IP（X-Forwarded-For
  末位取真实 IP 防伪造）、TTS 请求与缓存命中率、缓存体积、经典数
- 计数为进程内存统计，重启清零

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

server.py

@@ -4,6 +4,7 @@
 import hashlib
 import json
 import os
+import time
 import urllib.error
 import urllib.request
 from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer
@@ -39,6 +40,10 @@ PORT = int(os.environ.get("PORT", "8000"))
 
 GENERATION_URL = f"{DASHSCOPE_BASE}/services/aigc/multimodal-generation/generation"
 
+# 运行期统计：进程内存内计数，重启清零
+STATS = {"start": time.time(), "tts_requests": 0, "cache_hits": 0}
+VISITORS = set()  # 见过的客户端 IP（本次进程生命周期内）
+
 
 def http_post_json(url: str, payload: dict, headers: dict, timeout: int = 60) -> dict:
     """发送 JSON POST 请求并返回解析后的响应。"""
@@ -72,8 +77,29 @@ class Handler(SimpleHTTPRequestHandler):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, directory=str(BASE_DIR), **kwargs)
 
+    def _track_visitor(self) -> None:
+        """记录客户端 IP 到访客集合；nginx 反代后真实来源在 X-Forwarded-For / X-Real-IP。"""
+        # nginx 把真实 IP 追加在 X-Forwarded-For 末尾，取最后一个元素防伪造
+        xff = (self.headers.get("X-Forwarded-For") or "").split(",")[-1].strip()
+        ip = xff or (self.headers.get("X-Real-IP") or "").strip() or self.client_address[0]
+        VISITORS.add(ip)
+
     def do_GET(self) -> None:
-        """处理 GET 请求：/api/sutras 返回经典目录清单，其余按静态文件处理。"""
+        """处理 GET 请求：/api/* 接口，其余按静态文件处理。"""
+        self._track_visitor()
+        if self.path == "/api/stats":
+            cache_files = list(CACHE_DIR.glob("*.wav")) if CACHE_DIR.is_dir() else []
+            self._send_json({
+                "uptime_sec": int(time.time() - STATS["start"]),
+                "tts_requests": STATS["tts_requests"],
+                "cache_hits": STATS["cache_hits"],
+                "cache_files": len(cache_files),
+                "cache_bytes": sum(f.stat().st_size for f in cache_files),
+                "sutra_count": len(list(SUTRA_DIR.glob("*.json"))) if SUTRA_DIR.is_dir() else 0,
+                "visitors": len(VISITORS),
+                "model": TTS_MODEL,
+            })
+            return
         if self.path == "/api/sutras":
             try:
                 items = []
@@ -95,6 +121,7 @@ class Handler(SimpleHTTPRequestHandler):
 
     def do_POST(self) -> None:
         """处理 POST 请求，目前仅支持 /api/tts。"""
+        self._track_visitor()
         if self.path != "/api/tts":
             self._send_json({"error": "not found"}, status=404)
             return
@@ -119,8 +146,10 @@ class Handler(SimpleHTTPRequestHandler):
 
         cache_key = hashlib.sha256(f"{TTS_MODEL}|{voice}|{text}".encode("utf-8")).hexdigest()[:24]
         cache_file = CACHE_DIR / f"{cache_key}.wav"
+        STATS["tts_requests"] += 1
         try:
             if cache_file.exists():
+                STATS["cache_hits"] += 1
                 audio = cache_file.read_bytes()
             else:
                 audio = synthesize(text, voice)