Harden the content contracts and enforce the slug rule

pb/pb_migrations/collections_schema.json

@@ -74,7 +74,7 @@
         "max": 0,
         "min": 0,
         "name": "slug",
-        "pattern": "",
+        "pattern": "^[a-z0-9]+(-[a-z0-9]+)*$",
         "presentable": false,
         "primaryKey": false,
         "required": true,
@@ -298,7 +298,7 @@
         "max": 0,
         "min": 0,
         "name": "slug",
-        "pattern": "",
+        "pattern": "^[a-z0-9]+(-[a-z0-9]+)*$",
         "presentable": false,
         "primaryKey": false,
         "required": true,
@@ -388,7 +388,7 @@
         "pattern": "",
         "presentable": false,
         "primaryKey": false,
-        "required": false,
+        "required": true,
         "system": false,
         "type": "text"
       },
@@ -399,7 +399,7 @@
         "maxSelect": 1,
         "name": "topic",
         "presentable": false,
-        "required": false,
+        "required": true,
         "system": false,
         "type": "select",
         "values": [