fix(openclaw-acp): suppress silent no-reply output

[onutc]

Summary

• suppress OpenClaw NO_REPLY silent control text in the ACP bridge before it becomes ACP-visible assistant output
• cover transcript replay and live delta handling, including lead fragments like NO_ and glued NO_REPLY... text
• document the ownership boundary so OpenClaw sentinel handling stays in the bridge and the Slack gateway stays ACP-generic

Testing

• cd /Users/onur/repos/spritz/cli && pnpm exec node --test --import tsx ../images/examples/openclaw/acp-wrapper.test.ts
• cd /Users/onur/repos/spritz && npx -y @simpledoc/simpledoc check

[onutc]

Superseded by #219 after restacking this work on top of current main without the already-merged commit from #217.