Update feed query DTO (#232)

### Description

<!-- Provide a comprehensive description here about what your PR aims to
solve. -->

<!-- You may also add additional context -->

- Make limit and offset optional
- Parse string numeric values for limit and offset
- Remove default values from DTO definition

Fixes #231 
---

### PR Checklist

<!-- Please do not remove this section -->

<!-- Mark each item with an "x" ([ ] becomes [x]) -->

- [x] Read the Developer's Guide in
[CONTRIBUTING.md](https://github.com/yamcodes/bedstack/blob/main/CONTRIBUTING.md)
- [x] Use a concise title to represent the changes introduced in this PR
- [x] Provide a detailed description of the changes introduced in this
PR, and, if necessary, some screenshots
- [x] Reference an issue or discussion where the feature or changes have
been previously discussed
- [x] Add a failing test that passes with the changes introduced in this
PR, or explain why it's not feasible
- [x] Add documentation for the feature or changes introduced in this PR
to the docs; you can run them with `bun docs`


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Improvements**
* Article feed query parameters `limit` and `offset` are now optional,
with default values automatically applied when omitted. This provides
greater flexibility for querying articles and simplifies common use
cases.

<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: yamcodes

src/articles/dto/article-feed-query.dto.ts

@@ -1,21 +1,15 @@
 import { type } from 'arktype';
-import {
-  DEFAULT_LIMIT,
-  DEFAULT_OFFSET,
-  MAX_LIMIT,
-  MIN_LIMIT,
-  MIN_OFFSET,
-} from '@/shared/constants';
+import { MAX_LIMIT, MIN_LIMIT, MIN_OFFSET } from '@/shared/constants';
 
 /**
  * DTO for article feed query parameters.
  * Uses offset-based pagination with the following constraints:
- * - limit: number of items per request (default: DEFAULT_LIMIT, min: MIN_LIMIT, max: MAX_LIMIT)
- * - offset: number of items to skip (default: DEFAULT_OFFSET, min: MIN_OFFSET)
+ * - limit: number of items per request (min: MIN_LIMIT, max: MAX_LIMIT)
+ * - offset: number of items to skip (min: MIN_OFFSET)
  */
 export const ArticleFeedQueryDto = type({
-  limit: `${MIN_LIMIT} <= number.integer <= ${MAX_LIMIT} = ${DEFAULT_LIMIT}`,
-  offset: `number.integer >= ${MIN_OFFSET} = ${DEFAULT_OFFSET}`,
+  'limit?': `string.numeric.parse |> ${MIN_LIMIT} <= number.integer <= ${MAX_LIMIT}`,
+  'offset?': `string.numeric.parse |> number.integer >= ${MIN_OFFSET}`,
 });
 
 export type ArticleFeedQueryDto = typeof ArticleFeedQueryDto.infer;