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)