refactor: event delegation, unified subscription cleanup, centralized listing status helpers

js/components/pages/page-listing.js

@@ -23,14 +23,16 @@ class PageListing extends HTMLElement {
 
     connectedCallback() {
         this.listingId = this.dataset.id
+        this._unsubs = []
         this.render()
         this.loadListing()
-        this.unsubscribe = i18n.subscribe(() => this.render())
+        this._unsubs.push(i18n.subscribe(() => this.render()))
         window.addEventListener('currency-changed', this.handleCurrencyChange)
     }
 
     disconnectedCallback() {
-        if (this.unsubscribe) this.unsubscribe()
+        this._unsubs.forEach(fn => fn())
+        this._unsubs = []
         window.removeEventListener('currency-changed', this.handleCurrencyChange)
         this.resetMetaTags()
     }