PRXT - feat: lazy load tweet embeds

[punk6529]

Summary

• load the Tweet embed dynamically in DropPartMarkdown with a loading skeleton fallback to avoid bundling react-tweet eagerly
• update the DropPartMarkdown test harness to mock next/dynamic, ensure prior behaviours continue to work, and cover the lazy-loading behaviour

Testing

• npm run lint (passes with existing warnings in unrelated files)
• npm run type-check (fails: project-wide test typings currently error in many pre-existing suites)
• npm run test (fails: numerous suites abort because BASE_ENDPOINT isn’t set to an allowlisted domain in this environment)

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https://chatgpt.com/codex/tasks/task_e_68c94060e4c8832197e27b2682a686da

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[prxt6529]

Will be done in #1497