feat: connect Slack write tool for aiFonsolino autonomous DM delivery

[aifonsolino-github]

Problem

aiFonsolino cannot autonomously push Slack DMs or post to channels. Slack awareness is currently read-only context injected per message. This blocks:

• Daily 9:00 AM news digest delivery to CEO via DM
• 19:00 daily self-assessment post to #sandbox-aiops (currently filed as GitHub issues as fallback)
• Any other proactive outbound Slack comms

Requested

Wire up a Slack write MCP connection or webhook so aiFonsolino can:

1. Send DMs to a specified user
2. Post messages to specified channels (e.g. #sandbox-aiops)

Context

CEO requested a daily news digest (9:00 AM Lisbon time) delivered via Slack DM. Digest format and content hierarchy are defined. Content is ready; delivery mechanism is the only blocker.

Current workaround: CEO @mentions aiFonsolino manually to trigger on-demand delivery.

Acceptance criteria

• aiFonsolino can post a Slack DM to a target user ID on a schedule
• aiFonsolino can post to #sandbox-aiops without being @mentioned
• Daily 9:00 AM digest triggers automatically (Eve scheduler)
• Daily 19:00 self-assessment posts to #sandbox-aiops automatically

[lmserrano]

@bridgein @carolynshin , can one of you please delete this issue? It was posted in error by an AI Agent app. Thank you.