feat: implement pagination for user retrieval and update feed fetching logic

thoughts-backend/models/src/queries/mod.rs

@@ -1 +1,2 @@
+pub mod pagination;
 pub mod user;

thoughts-backend/models/src/queries/pagination.rs

@@ -0,0 +1,27 @@
+use serde::Deserialize;
+use utoipa::IntoParams;
+
+const DEFAULT_PAGE: u64 = 1;
+const DEFAULT_PAGE_SIZE: u64 = 20;
+
+#[derive(Deserialize, IntoParams)]
+pub struct PaginationQuery {
+    #[param(nullable = true, example = 1)]
+    page: Option<u64>,
+    #[param(nullable = true, example = 20)]
+    page_size: Option<u64>,
+}
+
+impl PaginationQuery {
+    pub fn page(&self) -> u64 {
+        self.page.unwrap_or(DEFAULT_PAGE).max(1)
+    }
+
+    pub fn page_size(&self) -> u64 {
+        self.page_size.unwrap_or(DEFAULT_PAGE_SIZE).max(1)
+    }
+
+    pub fn offset(&self) -> u64 {
+        (self.page() - 1) * self.page_size()
+    }
+}

thoughts-backend/models/src/schemas/mod.rs

@@ -1,4 +1,5 @@
 pub mod api_key;
+pub mod pagination;
 pub mod search;
 pub mod thought;
 pub mod user;

thoughts-backend/models/src/schemas/pagination.rs

@@ -0,0 +1,12 @@
+use serde::Serialize;
+use utoipa::ToSchema;
+
+#[derive(Serialize, ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct PaginatedResponse<T> {
+    pub items: Vec<T>,
+    pub page: u64,
+    pub page_size: u64,
+    pub total_pages: u64,
+    pub total_items: u64,
+}