Notify test

Test the notification system end-to-end.

Argument: $ARGUMENTS — optional channel name (e.g. slack). If omitted, tests every enabled channel.

Steps:

1. Read config and list enabled channels.

   bash

2. If $ARGUMENTS is set: restrict to that one channel.

3. Fire a test through each channel using CN_FORCE_CHANNELS:

   bash

4. Tail the log and surface any failed lines so the user knows which channels broke:

   bash

Report a tight summary: which channels were tested, which logged a failure, and where to look next (~/.claude-notifications/logs/notify.log). Do not list the channels' full config back at the user.