feat: user-customizable event voice rules (gift/blind box/enter/follow/like/guard/super chat)

- New event_rules.py: load/save event_rules.json, robust template renderer
  (missing vars -> empty, empty template -> muted), guard level mapping
- danmaku_handler.py: custom SEND_GIFT callback to extract blind_gift_name;
  implements all event callbacks feeding the TTS queue per user rules
- server.py: GET/POST /api/rules, load rules at startup, pass to client
- Web UI: 'Event Voice Rules' panel (per-event toggle + template + save)
- main.py CLI loads rules; build.py bundles event_rules.json
- skip_free_gift option to mute silver free gifts
- Rebuild portable zip (83.8 MB)

event_rules.json

@@ -0,0 +1,27 @@
+{
+  "enabled": {
+    "danmaku": true,
+    "gift": true,
+    "blind_box": true,
+    "enter_room": true,
+    "follow": false,
+    "like": false,
+    "interact_other": false,
+    "buy_guard": true,
+    "guard_toast": false,
+    "super_chat": true
+  },
+  "templates": {
+    "danmaku": "{uname}说、 {msg}",
+    "gift": "感谢由{viewer_name}投喂的{gift_name}",
+    "blind_box": "感谢由{viewer_name}投喂的{gift_name}爆出了{blind_box_gift}",
+    "enter_room": "欢迎{viewer_name}进入直播间",
+    "follow": "",
+    "like": "",
+    "interact_other": "",
+    "buy_guard": "恭喜{ships_viewer_name}成为尊贵的{ships_level}",
+    "guard_toast": "",
+    "super_chat": "{viewer_name}的醒目留言：{super_chat_content}"
+  },
+  "skip_free_gift": true
+}