refactor: 🔥 Remove Server Actors

app/entities/server-metadata/page.mdx

@@ -7,12 +7,14 @@ export const metadata = {
 
 Contains metadata about a Versia instance, such as capabilities and endpoints. {{ className: 'lead' }}
 
-Not to be confused with [Server Actor](/entities/server-actor), which is a User representing an instance in the federation.
-
 <Note>
     This entity is only used as part of [Server Discovery](/federation/discovery#server-discovery), and not as part of federation.
 </Note>
 
+## The `null` Author
+
+On all entities that have an `author` field, the `author` can be `null` to represent the instance itself as the author (like ActivityPub's Server Actors). In this case, the instance's public key should be used to verify the entity.
+
 ## Entity Definition
 
 <Row>
@@ -63,6 +65,17 @@ Not to be confused with [Server Actor](/entities/server-actor), which is a User
             <Property name="shared_inbox" type="URI" required={false}>
                 URI to the instance's shared inbox, if supported.
             </Property>
+            <Property name="public_key" type="PublicKey" required={true}>
+                Public key of the instance.
+
+                ```typescript
+                type PublicKey = {
+                    public_key: string;
+                }
+                ```
+
+                - `public_key`: Public key of the instance. Must follow the [Versia Public Key](/signatures) format.
+            </Property>
             <Property name="moderators" type="URI" required={false}>
                 URI to [Collection](/structures/collection) of instance moderators.
 
@@ -120,6 +133,9 @@ Not to be confused with [Server Actor](/entities/server-actor), which is a User
                 "content": "https://social.jimjams.com/files/logo.webp"
             }
         },
+        "public_key": {
+            "public_key": "MCowBQYDK2VwAyEA9zhEMtQZetRl4QrLcz99i7jOa6ZVjX7aLfRUsMuKByI=" 
+        },
         "banner": null,
         "extensions": {
             "example.extension:monthly_active_users": 1000