feat(presentation): /federation/lookup and /federation/follow endpoints

crates/api-types/src/requests.rs

@@ -80,3 +80,9 @@ pub struct SearchQuery {
     pub page: Option<u64>,
     pub per_page: Option<u64>,
 }
+
+#[derive(serde::Deserialize, utoipa::ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct FollowRemoteRequest {
+    pub handle: String,
+}

crates/api-types/src/responses.rs

@@ -87,3 +87,12 @@ pub struct CreatedApiKeyResponse {
     /// Raw API key — shown only once at creation
     pub key: String,
 }
+
+#[derive(Serialize, utoipa::ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct RemoteActorResponse {
+    pub handle: String,
+    pub display_name: Option<String>,
+    pub avatar_url: Option<String>,
+    pub url: String,
+}