[Enhancement]: Advanced — Profile Export/Import (share configs across machines)

Problem

Users with multiple PCs want to replicate their SysManager configuration. There is no way to export/import settings.

Advanced (new group)

Shipped in v1.28.0 as a working Profile Export/Import tab (Advanced group).

What it does

Export SysManager's own configuration — theme/appearance and speed-test history — to a single portable JSON file. Tick which sections to include.
Import on another PC: the dialog shows what the profile contains and when/by-which-version it was made, then applies it after confirmation (selective per-section).
Version tracking — a profile from a newer, incompatible build is refused with a clear "update SysManager" message rather than silently mis-applied.
Only SysManager's own config is touched (never system settings), so an import is fully reversible — just import a different profile.

How it's built

ProfileService bundles a hard-coded catalog of config files into a versioned ConfigProfile and applies it back. Crucially, ApplySections writes only catalog-known sections using the catalog's own file names, so a tampered profile claiming a rogue key or a ..\evil.json path cannot drop files outside the config directory (covered by a negative test).
ProfileViewModel + ProfileView follow the existing async + DialogService confirmation + file-dialog conventions.

Verification

8 unit tests including the path-injection guard, schema-version gate, and a full export→import file round-trip.

Install: winget upgrade laurentiu021.SysManager or the portable .exe from the v1.28.0 release.