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-tauri/tauri.conf.json

@@ -4,9 +4,9 @@
   "version": "2026.8.4",
   "identifier": "com.gitty",
   "build": {
-    "beforeDevCommand": "npm run dev",
+    "beforeDevCommand": "npm run prepare:lfs && npm run dev",
     "devUrl": "http://127.0.0.1:1420",
-    "beforeBuildCommand": "npm run build",
+    "beforeBuildCommand": "npm run prepare:lfs && npm run build",
     "frontendDist": "../dist"
   },
   "app": {
@@ -41,6 +41,12 @@
   },
   "bundle": {
     "active": true,
+    "externalBin": [
+      "binaries/git-lfs"
+    ],
+    "resources": [
+      "binaries/git-lfs-LICENSE.txt"
+    ],
     "targets": [
       "nsis"
     ],