feat(rehype): Conditionally expand code tabs in .md with {mdExpandTabs}

[s1gr1d]

DESCRIBE YOUR PR

Improvement of #17745

The generated .md files are mostly consumed by LLMs. Expanding every tab group floods context with trivial variations (npm/yarn/pnpm, ESM/CJS) that any LLM can infer from a single example.

This PR makes tab expansion opt-in via {mdExpandTabs}:

• Default: only the first tab is included, with an "Also available for: yarn, pnpm" note listing the other tabs for completeness
• Opt-in: adding {mdExpandTabs} to any code fence in a group expands all tabs (for cases like Swift/ObjC, different runtime setup flows, client/server splits)
• Skill update: technical-docs now documents when to use {mdExpandTabs} vs. when to let tabs collapse

Example page: https://sentry-docs-git-sig-copy-page-all-snippets-conditional.sentry.dev/platforms/javascript/guides/hono.md

IS YOUR CHANGE URGENT?

Help us prioritize incoming PRs by letting us know when the change needs to go live.

• Urgent deadline (GA date, etc.):
• Other deadline:
• None: Not urgent, can wait up to 1 week+

SLA

• Teamwork makes the dream work, so please add a reviewer to your PRs.
• Please give the docs team up to 1 week to review your PR unless you've added an urgent due date to it.
  Thanks in advance for your help!

PRE-MERGE CHECKLIST

Make sure you've checked the following before merging your changes:

• Checked Vercel preview for correctness, including links
• PR was reviewed and approved by any necessary SMEs (subject matter experts)
• PR was reviewed and approved by a member of the Sentry docs team

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
develop-docs	Ready	Preview, Comment	May 26, 2026 2:12pm
sentry-docs	Ready	Preview, Comment	May 26, 2026 2:12pm

[sergical]

My concern is that some pages use tabs as completely different approaches and if the llm knows that it's available, it doesn't mean it knows how to do it. example https://sentry-docs-git-sig-copy-page-all-snippets-conditional.sentry.dev/platforms/javascript/guides/nextjs.md

escaped` typescript
import * as Sentry from "@sentry/nextjs";

Sentry.init({
  dsn: "___PUBLIC_DSN___",

  // Adds request headers and IP for users
  sendDefaultPii: true,
  // ___PRODUCT_OPTION_START___ performance
  tracesSampleRate: process.env.NODE_ENV === "development" ? 1.0 : 0.1,
  // ___PRODUCT_OPTION_END___ performance
  // ___PRODUCT_OPTION_START___ session-replay
  replaysSessionSampleRate: 0.1,
  replaysOnErrorSampleRate: 1.0,
  // ___PRODUCT_OPTION_END___ session-replay
  // ___PRODUCT_OPTION_START___ logs
  enableLogs: true,
  // ___PRODUCT_OPTION_END___ logs
  integrations: [
    // ___PRODUCT_OPTION_START___ session-replay
    Sentry.replayIntegration(),
    // ___PRODUCT_OPTION_END___ session-replay
  ],
});
end escaped `

*Also available for: Server, Edge*

also the fact that it's after the block might be confusing to llms since it could be thinking it's related to what's next vs what's before?