Bash and PowerShell guidance on background commands now depends on a check

What

Claude gets written instructions for each tool it can use. Two of them, for running commands in the background with run_in_background, now change depending on a check:

• Bash: when the check is false, the description of run_in_background no longer promises you will be notified when the command finishes. It ends with a different sentence instead: Only use this if you don't need the result immediately.
• PowerShell: the advice about Start-Sleep, run_in_background and polling is only included when a check for background support passes. Before, it was always included.

Why

Claude should stop being told to rely on background running or completion notices in setups where they do not apply.