fix(docs): export clean selected-language markdown from Copy page button

[g-despot]

Problem

The docs "Copy page" button copied page chrome and didn't produce real markdown. Reported by the team:

• copies headers / other page content that shouldn't be included
• the "markdown" output includes HTML tags / doesn't look right

Root cause: copyPageAsMarkdown scraped document.querySelector("article").innerText. The <article> wrapper includes breadcrumbs, the version badge, the mobile TOC, and the footer ("Edit this page", tags), and innerText is rendered text, not markdown (code fences, heading #, and link syntax are all lost).

Fix

Rewrote copyPageAsMarkdown to produce clean markdown:

• Scope extraction to .theme-doc-markdown (the content body; page chrome is a sibling outside it).
• Convert HTML → Markdown with turndown + turndown-plugin-gfm, dynamically imported inside the handler so the site still server-renders at build time (turndown touches the DOM).
• Capture only the currently-selected code language. The custom code Tabs render every language into the DOM and hide the non-selected ones, so the copy strips [aria-hidden="true"].
• Strip the remaining in-content chrome: default-tab label strips + inactive panels ([role="tablist"], [hidden]), decorative icons (img[alt=""]), the code-tab header controls (the .code container header — language selector, "API docs" link, "More info"), and Cloud/Academy badges.
• Preserve Prism code blocks as fenced blocks with the correct language tag and line breaks.
• Robustness: a new error copy state ("Copy failed"), a navigator.clipboard guard, and aria-live="polite" on the status label.

A reusable data-copy-exclude opt-out marker was added to CloudOnlyBadge and AcademyBadge so their text no longer leaks into the copied markdown.

Verification

• yarn build passes (exit 0).
• The turndown pipeline was validated against the real built DOM: page chrome excluded, selected-language-only confirmed by element counts (non-selected language code blocks drop to zero), code blocks fenced with language + line breaks, headings/links/lists correct, and Cloud/Academy badge text stripped.

Out of scope / follow-ups

• The llms-txt plugin path was intentionally not used, to keep this change self-contained.
• For a later PR: "View as markdown" builds a 404 when a page has no source and pins main (version drift); the prompts-variant copy doesn't use the new error state.

Files

• src/components/ContextualMenu/index.js — the fix
• src/components/CloudOnlyBadge/index.jsx, src/components/AcademyBadge/index.jsx — data-copy-exclude markers
• package.json, yarn.lock — add turndown + turndown-plugin-gfm

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca