feat: add "Last Online" column to client list and modal (Closes #3402) (#3405)

* feat: persist client last online and expose API

* feat(ui): show client last online in table and info modal

* i18n: add “Last Online” across locales

* chore: format timestamps as HH:mm:ss

web/html/inbounds.html

@@ -807,6 +807,7 @@
             defaultKey: '',
             clientCount: [],
             onlineClients: [],
+            lastOnlineMap: {},
             isRefreshEnabled: localStorage.getItem("isRefreshEnabled") === "true" ? true : false,
             refreshing: false,
             refreshInterval: Number(localStorage.getItem("refreshInterval")) || 5000,
@@ -835,6 +836,7 @@
                     return;
                 }
 
+                await this.getLastOnlineMap();
                 await this.getOnlineUsers();
                 
                 this.setInbounds(msg.obj);
@@ -849,6 +851,11 @@
                 }
                 this.onlineClients = msg.obj != null ? msg.obj : [];
             },
+            async getLastOnlineMap() {
+                const msg = await HttpUtil.post('/panel/api/inbounds/lastOnline');
+                if (!msg.success || !msg.obj) return;
+                this.lastOnlineMap = msg.obj || {}
+            },
             async getDefaultSettings() {
                 const msg = await HttpUtil.post('/panel/setting/defaultSettings');
                 if (!msg.success) {
@@ -1493,6 +1500,17 @@
             isClientOnline(email) {
                 return this.onlineClients.includes(email);
             },
+            getLastOnline(email) {
+                return this.lastOnlineMap[email] || null
+            },
+            formatLastOnline(email) {
+                const ts = this.getLastOnline(email)
+                if (!ts) return '-'
+                if (this.datepicker === 'gregorian') {
+                    return DateUtil.formatMillis(ts)
+                }
+                return DateUtil.convertToJalalian(moment(ts))
+            },
             isRemovable(dbInboundId) {
                 return this.getInboundClients(this.dbInbounds.find(row => row.id === dbInboundId)).length > 1;
             },