feat(git-lfs): add Git LFS status and sidecar bundling

Adds Git LFS support to the backend API and related UI.
The app now exposes commands to inspect, install, track and pull.
A sidecar git-lfs binary is bundled and a prep script is added.
This prepares the correct binary for each target platform.

- Expose Git LFS status and management commands in API
- Bundle and prepare a sidecar git-lfs binary for targets
- Update packaging, docs, and README with LFS notes

PKGBUILD

@@ -7,7 +7,7 @@ pkgdesc="A lightweight, modern Git client built with Tauri"
 arch=('x86_64')
 url="https://git.cbsk-tech.de/Christoph/GitLite"
 license=('MIT')
-depends=('webkit2gtk-4.1' 'gtk3' 'git' 'hicolor-icon-theme' 'libappindicator-gtk3' 'librsvg' 'xdotool')
+depends=('webkit2gtk-4.1' 'gtk3' 'git' 'git-lfs' 'hicolor-icon-theme' 'libappindicator-gtk3' 'librsvg' 'xdotool')
 makedepends=('rust' 'nodejs' 'npm')
 options=('!lto' '!debug')