Add local cache and fallback for default subplebbits

src/data/default-subplebbits.json

@@ -0,0 +1,19 @@
+{
+  "title": "5chan directories",
+  "description": "Each 5chan directory is assigned to a board (subplebbit) handpicked by the team, until DAO curation is implemented.\n\nhttps://github.com/plebbit/temporary-default-subplebbits",
+  "createdAt": 1762179811,
+  "updatedAt": 1762179811,
+  "subplebbits": [
+    {
+      "title": "/pol/ - Politically Incorrect",
+      "address": "politically-incorrect.eth",
+      "nsfw": true
+    },
+    {
+      "title": "/biz/ - Business & Finance",
+      "address": "business-and-finance.eth",
+      "nsfw": false
+    }
+  ]
+}
+