Pwsh installer that detects arch, downloads
$Server/agent/binary?os=windows&arch=amd64 to
C:\Program Files\restic-manager\, runs the agent in -enroll-server
[+ -enroll-token] mode (token flow OR announce-and-approve), then
calls 'restic-manager-agent install' to register the SCM service.
Surfaces existing scheduled tasks named *restic* without disabling.
CLAUDE.md restage block updated to also stage install.ps1 alongside
install.sh.
