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)

build.py

@@ -145,6 +145,8 @@ def main() -> int:
     shutil.copy2(ROOT / "tts_bridge.js", BUILD_DIR / "tts_bridge.js")
     shutil.copy2(ROOT / "english-kana-matcher.js", BUILD_DIR / "english-kana-matcher.js")
     shutil.copy2(ROOT / "package.json", BUILD_DIR / "package.json")
+    if (ROOT / "event_rules.json").exists():
+        shutil.copy2(ROOT / "event_rules.json", BUILD_DIR / "event_rules.json")
     print("  OK")
 
     # ── 6. Launcher ────────────────────────────────────────────────────