feat: add Postiz app, fix silent() for || fallbacks

frontend/public/json/postiz.json

@@ -0,0 +1,44 @@
+{
+    "name": "Postiz",
+    "slug": "postiz",
+    "categories": [
+        19
+    ],
+    "date_created": "2026-02-22",
+    "type": "ct",
+    "updateable": true,
+    "privileged": false,
+    "interface_port": 80,
+    "documentation": "https://docs.postiz.com/",
+    "website": "https://postiz.com/",
+    "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/postiz.webp",
+    "config_path": "/opt/postiz/.env",
+    "description": "Postiz is an AI-powered social media scheduling tool for managing posts, building audiences, and growing your business across platforms like X, LinkedIn, Instagram, TikTok, Reddit, and more.",
+    "install_methods": [
+        {
+            "type": "default",
+            "script": "ct/postiz.sh",
+            "resources": {
+                "cpu": 4,
+                "ram": 8192,
+                "hdd": 20,
+                "os": "Debian",
+                "version": "13"
+            }
+        }
+    ],
+    "default_credentials": {
+        "username": null,
+        "password": null
+    },
+    "notes": [
+        {
+            "text": "The build process requires significant RAM (4GB+). Do not reduce container RAM below 4GB.",
+            "type": "warning"
+        },
+        {
+            "text": "NEXT_PUBLIC_* variables are baked at build time. If you change the IP/URL, rebuild with: cd /opt/postiz && pnpm run build",
+            "type": "info"
+        }
+    ]
+}