Feature Request: PowerShell Profile Support

[grave0x]

Summary

Add support for managing PowerShell profiles (both Windows PowerShell Profile.ps1 and PowerShell Core Microsoft.PowerShell_profile.ps1) as first-class dwell entries.

Motivation

PowerShell is the primary shell on Windows and widely used cross-platform. Users need to manage their PowerShell profile scripts alongside bash, zsh, fish, and other dotfiles.

Proposed behavior

• dwell add $PROFILE should detect PowerShell profiles and copy them into the source directory with the appropriate prefix (e.g. dot_powershell/Microsoft.PowerShell_profile.ps1).
• Template rendering should work on .ps1.tmpl files.
• source_to_target() should correctly resolve PowerShell profile paths across Windows (%USERPROFILE%\Documents\PowerShell) and non-Windows (~/.config/powershell/).

Implementation notes

• $PROFILE on Windows points to %USERPROFILE%\Documents\PowerShell\Microsoft.PowerShell_profile.ps1
• Cross-platform PowerShell Core uses ~/.config/powershell/Microsoft.PowerShell_profile.ps1
• The existing EntryKind::from_filename() could handle dot_powershell/ prefixed files
• The source_to_target() function in dwell-core/src/types.rs would need a new PowerShell mapping
• No existing tests cover PowerShell paths

Acceptance criteria

• dwell add $PROFILE works on Windows
• dwell add ~/.config/powershell/Microsoft.PowerShell_profile.ps1 works on Linux/macOS
• source_to_target() maps dot_powershell/profile.ps1 to the correct target path
• Template files with .ps1.tmpl extension render correctly
• Integration tests added for PowerShell paths