Show 'Fleet will try again.' in host activity feed for NotNow MDM commands

[kilo-code-bot]

Summary

• Adds "Fleet will try again." text to the host-level activity feed for MDM commands with a "NotNow" status, matching the existing behavior in the CommandDetailsModal.
• Previously, users had to open the modal to see this retry information; now it's visible directly in the activity feed.

Changes

• frontend/pages/hosts/details/cards/Activity/CommandItem/CommandItem.tsx: When a command's status is "NotNow", append " Fleet will try again." to the activity text displayed in the feed.

QA

1. Navigate to a host details page with MDM commands enabled.
2. Trigger or find a command with "NotNow" status (host locked or running on battery in Power Nap).
3. Verify the activity feed item shows "The {command} command is deferred. Fleet will try again."
4. Verify the CommandDetailsModal still shows the full deferred message with "Fleet will try again."

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Built for Mel Pike by Kilo for Slack

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.79%. Comparing base (f70a02a) to head (3609f7d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #44532   +/-   ##
=======================================
  Coverage   66.79%   66.79%           
=======================================
  Files        2637     2637           
  Lines      212132   212133    +1     
  Branches     9437     9438    +1     
=======================================
+ Hits       141688   141689    +1     
  Misses      57578    57578           
  Partials    12866    12866           

Flag	Coverage Δ
frontend	54.78% <100.00%> (+<0.01%)	⬆️

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