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

src/App.svelte

@@ -4,7 +4,7 @@
   import { getCurrentWindow } from "@tauri-apps/api/window";
   import { open as openDialog } from "@tauri-apps/plugin-dialog";
   import { check, type DownloadEvent, type Update } from "@tauri-apps/plugin-updater";
-  import { AlertCircle, Cherry, Download, FolderOpen, GitBranch, GitMerge, LoaderCircle, Plus, Search, Star, X } from "@lucide/svelte";
+  import { AlertCircle, Cherry, CloudOff, Download, FolderOpen, GitBranch, GitMerge, LoaderCircle, Plus, Search, Star, X } from "@lucide/svelte";
   import { beginFrontendShutdown } from "./lib/telemetry";
 
   import TitleBar from "./lib/TitleBar.svelte";
@@ -506,7 +506,11 @@
   $: canCompare = hasRepository && compareFrom.length > 0 && compareTo.length > 0 && compareFrom !== compareTo && !isBusy;
   $: localBranches = branches.filter((b) => !b.remote);
   $: localBranchNames = localBranches.map((b) => b.name);
+  $: localBranchUpstreams = Object.fromEntries(
+    localBranches.flatMap((branch) => branch.upstream ? [[branch.name, branch.upstream]] : []),
+  ) as Record<string, string>;
   $: remoteBranches = branches.filter((b) => b.remote);
+  $: currentBranchIsLocalOnly = Boolean(status?.current_branch) && !status?.upstream;
   $: repoSearchTerm = repoSearch.trim().toLowerCase();
   $: openRepoRows = repoTabs.filter((repo) => repoMatchesSearch(repo, repoSearchTerm));
   $: recentRepoRows = recentRepoPaths
@@ -4445,6 +4449,7 @@
         {operation}
         ahead={status?.ahead ?? 0}
         behind={status?.behind ?? 0}
+        localOnly={currentBranchIsLocalOnly}
         language={appLanguage}
         editorName={editorToolName}
         terminalName={terminalToolName}
@@ -4896,9 +4901,22 @@
             {/if}
           </div>
           <div class="sync-stats" aria-label="Sync state">
-            {#if status?.upstream}<span title="Upstream">{status.upstream}</span>{/if}
-            <strong>{status?.ahead ?? 0} ahead</strong>
-            <strong>{status?.behind ?? 0} behind</strong>
+            {#if currentBranchIsLocalOnly}
+              <span
+                class="sync-local-only"
+                title={appLanguage === "de"
+                  ? "Dieser Branch existiert nur auf diesem Computer. Veröffentlichen richtet den Remote-Branch ein."
+                  : "This branch exists only on this computer. Publish configures its remote branch."}
+              >
+                <CloudOff size={11} aria-hidden="true" />
+                <strong>{appLanguage === "de" ? "Nur lokal" : "Local only"}</strong>
+                <small>{appLanguage === "de" ? "noch nicht veröffentlicht" : "not published yet"}</small>
+              </span>
+            {:else}
+              {#if status?.upstream}<span title="Upstream">{status.upstream}</span>{/if}
+              <strong>{status?.ahead ?? 0} ahead</strong>
+              <strong>{status?.behind ?? 0} behind</strong>
+            {/if}
           </div>
         </div>
 
@@ -4991,6 +5009,7 @@
           {commits}
           {selectedCommitHash}
           {localBranchNames}
+          {localBranchUpstreams}
           remoteBranchNames={remoteBranches.map((branch) => branch.name)}
           activeBranch={status?.current_branch ?? ""}
           activeUpstream={status?.upstream ?? ""}
@@ -5027,8 +5046,14 @@
       <span class="workspace-status-spacer"></span>
       {#if workspaceActive}
         <span class="workspace-branch"><GitBranch size={12} aria-hidden="true" />{status?.current_branch ?? "No branch"}</span>
-        <span class="ahead">↑ {status?.ahead ?? 0}</span>
-        <span class="behind">↓ {status?.behind ?? 0}</span>
+        {#if currentBranchIsLocalOnly}
+          <span class="workspace-local-only" title={appLanguage === "de" ? "Branch noch nicht veröffentlicht" : "Branch not published yet"}>
+            <CloudOff size={11} aria-hidden="true" />{appLanguage === "de" ? "Nur lokal" : "Local only"}
+          </span>
+        {:else}
+          <span class="ahead">↑ {status?.ahead ?? 0}</span>
+          <span class="behind">↓ {status?.behind ?? 0}</span>
+        {/if}
         <span class:active={autoRefreshEnabled} class="workspace-auto">Auto <i aria-hidden="true"></i></span>
       {/if}
       {#if appVersion}<span class="app-version" title={`Gitty version ${appVersion}`}>Gitty v{appVersion}</span>{/if}