Add a WordPress media-library upload response fixture

[yoldaolmak]

Problem

Pictovap's WordPress adapter depends on media-library responses from the WordPress REST API. New contributors should be able to verify that mapping without a live WordPress site, credentials, or private media.

Scope

Add one small fixture-driven regression test around WordPressUploader.upload_media().

A good PR should:

• add a synthetic WordPress media upload response fixture under tests/fixtures/wordpress/;
• mock the media upload response and the follow-up metadata update request;
• assert that the returned result preserves media_id, url, alt_text, caption, and provider-safe metadata;
• keep all URLs, credentials, usernames, and file paths fake;
• avoid network calls.

Acceptance criteria

• make contributor-smoke and make contribution-check pass.
• The new test fails if the WordPress response no longer maps the media ID or source URL correctly.
• No real WordPress host, token, password, or media URL is required.

Contributor path

This is contribution: no-claim: fork the repo and open a PR directly. No reservation comment is needed.

[yoldaolmak]

Maintainer update: this issue is still open and now has a faster setup check. Before editing the WordPress fixture, run:

make install
make contributor-smoke

Then keep the PR focused on one mocked media-library response fixture plus the mapping assertion. No live WordPress site, media URL, username, token, or private file path is needed.

[yoldaolmak]

Maintainer update: this issue now has a copy-paste First PR Kit with exact files, focused test command, expected PR size, and boundaries:

https://github.com/yoldaolmak/Pictovap/blob/main/docs/contributing/first-pr-kits.md

No claim comment is needed. Fork the repo, keep the PR focused on this single issue, and paste the focused test output in the PR body.