feat(docs): copy markdown + share-link in ask widget

[AztecBot]

Mirrors the two features just landed in honk-ai#131 over to AztecDocsWidget, which is what docs.aztec.network actually ships (honk-ai's /ask is a separate frontend). Same UX, same security posture.

What it does

1. Copy raw markdown

Small Copy chip on each assistant message header. Writes the raw markdown text (with backticks, headers, lists, fences) to the clipboard so it survives a paste into Slack/Notion/GitHub. Uses the async Clipboard API where available and falls back to a hidden <textarea> + document.execCommand("copy") for sandboxed iframes / older WebViews.

2. Share link

Share button in the panel header (visible once the conversation has at least one finished reply). It encodes the current Q&A as JSON → UTF-8 → gzip (CompressionStream) → base64url, slots it into the URL hash as …/<page>#share=<blob>, and copies the link.

When someone opens that link:

• the widget detects #share=… on mount, decodes locally, replays the transcript, and auto-opens the panel
• a status banner ("Viewing a shared conversation. Start a new one") appears at the top of the panel
• as soon as the recipient hits send (or clicks reset), the banner clears and the hash is scrubbed via history.replaceState so a refresh doesn't reload the old transcript over their new one

The encoded blob never leaves the browser — URL fragments are not sent to the origin, so this preserves the existing anonymous-no-persist posture (no DB, no new endpoints, no backend touch). A roundtrip of a small conversation lands around ~280 bytes; the codec hard-caps encoded output at 32 KiB.

Implementation notes

• New module: docs/src/components/AztecDocsWidget/share.js — versioned wire format { v: 1, m: [{ r: "u"|"b", t, s? }] }, plus readShareHash / buildShareUrl / clearShareHash helpers and a shared copyToClipboard helper reused by the Copy button.
• index.jsx — hash-replay useEffect on mount that pairs flat {role,text} entries back into the widget's {prompt, response, sources} message shape; handleShare callback; clears viewingShared / hash on new handleSend or handleReset.
• Panel.jsx — Share button in the header (styled inline to read theme tokens, with .azw-share-btn.is-ok / .is-fail overrides for the post-click state); shared-conversation banner above the body.
• Message.jsx — CopyMarkdownButton rendered in the assistant role header on completed (non-streaming, non-empty) replies, after the existing feedback wiring from feat(docs): user feedback + surfaced error frames in docs ask widget #23288.
• styles.css — minimal additions for the share-button success/fail states.

Test plan

• yarn preprocess && yarn docusaurus build — clean (the two broken-anchor warnings are pre-existing in the CLI reference, unrelated to this change)
• Babel parse-check on all four touched JSX files + node --check on share.js
• Node roundtrip of the share codec over a sample 4-message conversation (encodes to ~280 bytes, decodes back to identical structure, malformed token returns null)
• Manual browser smoke: ask a question, click Copy, paste to verify markdown survives; click Share, open the copied URL in a new tab, verify the panel auto-opens with the banner; hit send and verify the banner clears + hash is scrubbed

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Created by claudebox · group: slackbot