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

src/lib/types.ts

@@ -193,6 +193,34 @@ export interface GitRepositoryFile {
   status: FileStatusKind | null;
 }
 
+export interface GitLfsPattern {
+  pattern: string;
+  source: string;
+  lockable: boolean;
+  tracked: boolean;
+}
+
+export interface GitLfsFile {
+  name: string;
+  size: number;
+  checkout: boolean;
+  downloaded: boolean;
+  oid_type: string;
+  oid: string;
+  version: string;
+}
+
+export interface GitLfsStatus {
+  available: boolean;
+  bundled: boolean;
+  version: string | null;
+  filters_configured: boolean;
+  hook_installed: boolean;
+  repository_uses_lfs: boolean;
+  patterns: GitLfsPattern[];
+  files: GitLfsFile[];
+}
+
 export interface RepositoryBundle {
   status: GitStatus;
   branches: GitBranch[];