feat(git): add upstream tracking and local-only branch UI

This release adds upstream tracking for branches and a local-only
indicator in the UI.
The Git integration now exposes upstreams and supports publish flows.
This enables publishing and remote-tracking configuration.

- Introduces upstream tracking and local-only branch UI markers
- Updates toolbar to reflect publish-local state and status indicators
- Bumps version to 2026.8.3 and updates changelog

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "gitty",
-  "version": "2026.8.2",
+  "version": "2026.8.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "gitty",
-      "version": "2026.8.2",
+      "version": "2026.8.3",
       "dependencies": {
         "@lucide/svelte": "^1.21.0",
         "@tailwindcss/vite": "^4.3.1",