feat: support daemon service install in user permission instead of root permission

[AnnatarHe]

Currently, the Linux daemon installation process still uses root permissions. Can you change it to user scope?

The file is located in model/daemon-installer.linux.go.

You can refer to the same process in model/daemon-installer.darwin.go.

@claude

[claude]

Claude finished @AnnatarHe's task —— View job • claude/issue-116-20251003-0835 • Create PR ➔

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Completed ✅

Tasks

• Read the Darwin (macOS) implementation to understand user-scope pattern
• Read the current Linux implementation
• Modify Linux installer to use systemd user services
• Commit and push changes
• Provide PR link

Changes Made

model/daemon-installer.linux.go:

• Added os/user import to get current user home directory
• Updated all systemctl commands to use --user flag
• Changed service path from /etc/systemd/system/ to ~/.config/systemd/user/
• Updated CheckAndStopExistingService() to match Darwin pattern (only stop if service is running)
• Updated RegisterService() to create user systemd directory and use user-scope paths
• Updated all service management methods to use user-scope commands

model/sys-desc/shelltime.service:

• Removed User=root and Group=root (service runs as current user)
• Changed WantedBy=multi-user.target to WantedBy=default.target (user target)

These changes make the Linux daemon installation work in user scope, matching the Darwin implementation pattern and eliminating the need for root permissions.

--- • Branch: claude/issue-116-20251003-0835