fix: replace set:html with plain text rendering in CareersPage translations

[cevheri]

Problem

src/page-templates/CareersPage.astro:90 uses set:html to render translation strings containing <br/> tags. While translation JSON is internal, this increases the blast radius of any compromised content pipeline.

Fix

Replace <br/> in translations with separate keys or use CSS for line breaks instead of HTML.

Priority

Low — translation files are internal, real risk is minimal.

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Source: PR #11 Copilot review (round 2)