[Fix] Discord follow-ups show raw prompt wrappers in the task transcript

[roomote-roomote]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

Related issue

Internal follow-up from Discord/transcript display.

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Discord follow-up prompts include structural wrappers (replying_to, discord_turn_policy, thread_context, communication_message). The task transcript was showing that raw markup instead of only the user's words.

normalizeTranscriptUserText now strips those Slack-parity prefixes the same way it already handles bare communication_message and Slack turns, so the UI shows just the user message body.

How it was tested

• Extended unit coverage in packages/types/src/__tests__/acp.test.ts for Discord prefixes (with and without thread_context), policy-only prefixes, and HTML-escaped wrappers
• pnpm --filter @roomote/types exec vitest run src/__tests__/acp.test.ts (77 tests passed)
• Pre-push: oxlint, residual lint, check-types:fast, knip

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-roomote]

No code issues found. See task

_{Reviewed e2fa7e2}