feat: multi-listener bridge + subscribe/unsubscribe in index page

src/common/bridge.js

@@ -1,12 +1,12 @@
-// DSHWatch bridge: @system.interconnect wrapper (real shell glue).
-// Sends/receives JSON envelopes to the DSHWatch phone APP over the Xiaomi
-// Vela interconnect BLE channel. Protocol per DSHWatch_Server/docs/PROTOCOL.md.
+// DSHWatch bridge: @system.interconnect wrapper.
+// Sends/receives JSON envelopes to the DSHWatch phone APP over the Vela BLE channel.
+// Protocol per DSHWatch_Server/docs/PROTOCOL.md.
 
 import interconnect from '@system.interconnect'
 
 let conn = null
 let seq = 0
-let listeners = []
+const listeners = new Set()
 let currentStatus = '未连接'
 
 function getConn() {
@@ -48,8 +48,13 @@ function emit(type, payload) {
   }
 }
 
+export function subscribe(callbacks) {
+  listeners.add(callbacks)
+  return () => listeners.delete(callbacks)
+}
+
 export function init(callbacks) {
-  listeners = [callbacks]
+  subscribe(callbacks)
   refreshConn()
 }