release: 1.6.0 — hide Portal page until it's fully implemented

Portal page is removed from the snap-in's nav entry list in composer.json
so it stops appearing in the sidebar. All portal routes, the
PortalController, the Portal.vue page, and the unifi.auth permission
are retained — we'll surface the page again in a later version once the
captive portal flow is fully working.

Minor bump because this is the first release that bundles the recent
batch of features:
* per-page access grants (snap-in-local table, super-admin only)
* cron logs tab with structured per-run history
* PPSK scheduling consistency + drift correction
* settings tabs (Connection / Tasks / Logs / Webhooks / Access)
* webhooks moved under /settings/webhooks + Test URL button
* embedded PPSK update via WLAN config
* page width standardized at max-w-7xl px-4

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

composer.json

@@ -1,7 +1,7 @@
 {
     "name": "dashboard/unifi",
     "description": "UniFi network management, WiFi stats, and captive portal authentication for the Dashboard platform",
-    "version": "1.5.5",
+    "version": "1.6.0",
     "type": "library",
     "license": "MIT",
     "autoload": {
@@ -27,7 +27,6 @@
                 { "label": "Devices",          "route_name": "unifi.devices",          "icon": "cpu-chip",         "permission": "unifi.stats",    "sort_order": 3 },
                 { "label": "Clients",          "route_name": "unifi.clients",          "icon": "users",            "permission": "unifi.stats",    "sort_order": 4 },
                 { "label": "WiFi Networks",    "route_name": "unifi.wifi",             "icon": "wifi",             "permission": "unifi.manage",   "sort_order": 5 },
-                { "label": "Portal",           "route_name": "unifi.portal.settings",  "icon": "shield-check",     "permission": "unifi.auth",     "sort_order": 6 },
                 { "label": "Settings",         "route_name": "unifi.settings",         "icon": "cog-6-tooth",      "permission": "unifi.settings", "sort_order": 99 }
             ],
             "permissions": [