[Improvement / Feature] AFK Mover: Add exempt channel IDs support

[Slipi089]

Feature Request: Exempt Channel IDs in AFK Mover

Description

The AFK Mover action currently supports exemptGroupIds to exclude clients by server group.
I would like to request a similar option for channels: exemptChannelIds.

Use Case

I have a channel (e.g. a lobby or a waiting room) where clients should NOT be moved to the AFK channel,
even if they exceed the idle threshold. Currently there is no way to exclude specific channels from the AFK mover logic.

Suggested Implementation

Similar to the existing exemptGroupIds logic in flow-runner.ts, add an exemptChannelIds field:

const exemptChannelIds = data.exemptChannelIds
  ? (await ctx.resolveTemplate(data.exemptChannelIds)).split(',').map(s => s.trim()).filter(Boolean)
  : [];

// In the client loop:
if (exemptChannelIds.length > 0 && exemptChannelIds.includes(String(cl.cid))) continue;

This would allow users to specify a comma-separated list of channel IDs to exclude from AFK moving.

Additional Context

The exemptGroupIds field already works great – this would be a natural extension of that existing feature.