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

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

[s1gr1d]

That's a valid concern. We could either put the comment above the snippet with "Other code snippet variations (not listed): ..." or we just remove the line again 🤔

[sergical]

@s1gr1d i actually think having all options be rendered in the markdown helps the agent have the right context, idk if im not thinking about edgecases where it really becomes a context issue, but having all of it available for agent to decide how to proceed vs just knowing that other options exist without knowing how to get them might be more optimal, curious what you think!