Fix docs content centering

[suhail-ak-2]

Summary

• Center docs pages through the DocItemLayout row/column instead of relying on the hidden desktop TOC column.
• Add a shared --doc-content-max-width value and reuse it for standard docs and generated index pages.
• Keep the section label aligned with the page title at the wider content width.

/claim tscircuit/docs-old#64

Note: I tried to comment /attempt #64, but tscircuit/docs-old is archived/read-only and GitHub rejected the comment because the issue is locked.

Verification

• bunx @biomejs/biome format src/theme/DocItem/Layout/index.tsx src/theme/DocItem/Layout/styles.module.css src/css/custom.css --write
• bun run typecheck
• bun run build
• git diff --check
• Desktop screenshot: bunx playwright screenshot --browser=chromium --viewport-size=1440,900 --wait-for-timeout=3000 http://127.0.0.1:3123/intro/installation /private/tmp/tscircuit-docs-after-install.png
• Mobile screenshot: bunx playwright screenshot --browser=chromium --viewport-size=390,844 --wait-for-timeout=3000 http://127.0.0.1:3123/intro/installation /private/tmp/tscircuit-docs-after-install-mobile.png

Risk

• This changes the docs layout wrapper, so the main visual risk is unintended width changes on uncommon generated-index or MDX-heavy pages. The max-width is centralized so follow-up tuning is one variable.

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	May 11, 2026 0:00am

[suhail-ak-2]

I found after opening this that #558 also includes a small docs-centering change and claims docs-old#64 among several other archived docs issues. This PR is intentionally a narrower alternative for just the layout/centering part, with desktop/mobile screenshots and full docs checks. Happy to close if maintainers prefer to take the broader #558 path.

[github-actions]

This PR has been automatically marked as stale because it has had no recent activity. It will be closed if no further activity occurs.

[github-actions]

This PR was closed because it has been inactive for 1 day since being marked as stale.