refactor(api): share Pagination across admin/public; cover get-by-id auth

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/api/src/public.rs

@@ -14,10 +14,10 @@ use axum::{
     routing::get,
 };
 use domain::{CatalogueObject, ObjectId};
-use serde::{Deserialize, Serialize};
+use serde::Serialize;
 use utoipa::ToSchema;
 
-use crate::AppState;
+use crate::{AppState, pagination::Pagination};
 
 /// A catalogue object as exposed on the public surface (public-safe fields only).
 #[derive(Serialize, ToSchema)]
@@ -50,26 +50,6 @@ pub(crate) struct PublicObjectPage {
     pub offset: i64,
 }
 
-/// Pagination query parameters with sane defaults and a hard cap.
-#[derive(Deserialize)]
-pub(crate) struct Pagination {
-    limit: Option<i64>,
-    offset: Option<i64>,
-}
-
-const DEFAULT_LIMIT: i64 = 50;
-const MAX_LIMIT: i64 = 200;
-
-impl Pagination {
-    fn limit(&self) -> i64 {
-        self.limit.unwrap_or(DEFAULT_LIMIT).clamp(1, MAX_LIMIT)
-    }
-
-    fn offset(&self) -> i64 {
-        self.offset.unwrap_or(0).max(0)
-    }
-}
-
 /// List public objects (paginated).
 #[utoipa::path(
     get,