Skill docs should explain how to resolve user mentions via rolodex

[zomglings]

Problem

The clacks skill documentation doesn't explain how to properly @mention users in Slack messages. When an AI assistant uses clacks send, it may naively write @username in the message text, which doesn't actually notify the user.

What happened

I was asked to post a message mentioning a specific user. I sent:

clacks send -c "#channel" -m "Hey @SomeUser - please review this PR"

This posted the message but @SomeUser was just plain text - no notification was sent. The user had to tell me to use the rolodex to resolve the user ID and use Slack's <@USER_ID> format.

The correct approach:

# First, find the user ID
clacks rolodex list -T user -l 500 | jq -r '.aliases[] | select(.alias | test("someuser"; "i"))'

# Then use the ID in the message
clacks send -c "#channel" -m "Hey <@U12345678> - please review this PR"

Suggested fix

Add a section to the skill docs explaining:

1. Plain @username in message text doesn't create a real mention
2. How to use clacks rolodex list -T user to find user IDs (with pagination via -l flag)
3. The correct Slack mention format: <@USER_ID> for users, <!channel> for @channel, etc.
4. Maybe a quick example workflow for mentioning someone

Additional context

The rolodex list defaults to 100 results, so if the user isn't in the first 100, you need to use -l 500 or paginate with --offset.

[zomglings]

Might be good to add a --resolve flag to clacks send which will autoresolve @-mentions and #-mentions via the rolodex or through the slack API.