fix: update urls to contact form

[mateuszlampert]

Description

Because of moving contact form from swmansion.com/contact/projects to swmansion.com/contact all of our contact links/buttons have stopped working. This PR updates urls in all Hire Us/Contact sections in our docs and README. Because our library (t-rex-ui) does not support customising the url, a HireUsButton component is added and styled as a copy of original HomepageButton.

Introduces a breaking change?

• Yes
• No

Type of change

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Documentation update (improves or adds clarity to existing documentation)
• Other (chores, tests, code style improvements etc.)

Tested on

• iOS
• Android

Testing instructions

• yarn build -> yarn serve
• check if all links in docs and README work

Screenshots

Before

Screen.Recording.2026-01-22.at.20.15.19.mov

After

Screen.Recording.2026-01-22.at.20.17.08.mov

Related issues

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings

Additional notes

Note: I added an issue in t-rex-ui library to make the component more customisable. We should make sure to move back to the original components after the issue is resolved, so we stay in sync with original library.

[msluszniak]

I tested two buttons from video included and readmes in all languages. All worked. So if these are all places with these links, feel free to merge :))