fix: scope Telegram pairing code blocks

[artemgetmann]

Summary

• port upstream commit 149c4683a3 for Telegram pairing message formatting
• keep pairing codes and approve commands wrapped as Telegram HTML code blocks in the fork
• adapt the new DM test to this fork's direct src/pairing/pairing-challenge.ts entrypoint instead of upstream's plugin-sdk wrapper
• carry the inherited doc-formatting fix required for pnpm check in this branch

Why

• pairing codes are easy to mistype when Telegram collapses or mangles plain text
• the upstream behavior is worth keeping, but this fork's pairing path differs enough that the test needed a manual port instead of a blind cherry-pick

Validation

• pnpm test -- extensions/telegram/src/dm-access.test.ts extensions/telegram/src/bot.create-telegram-bot.test.ts src/pairing/pairing-messages.test.ts src/pairing/pairing-challenge.test.ts
• pnpm build
• pnpm check

Risk

• low: behavior change is limited to Telegram pairing reply rendering and associated tests
• medium: this PR includes the same inherited docs formatting fix already needed on the prior intake branch so repo-wide check can pass