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

.gitignore

@@ -1,6 +1,9 @@
 /node_modules
 /dist
 /src-tauri/target
+/src-tauri/binaries/git-lfs
+/src-tauri/binaries/git-lfs.exe
+/src-tauri/binaries/git-lfs-*-*-*
 *.log
 .idea
 .DS_Store
@@ -9,4 +12,4 @@
 target
 
 *.pkg.tar.zst
-pkg
+pkg