add auto-updater and git workflow enhancements

This change introduces a comprehensive auto-update mechanism for the application and significant improvements to the integrated Git client experience.

Key features include:
- **Automated Release Workflow:** A new Gitea Actions workflow (`app_builder.yaml`) and a Python `cicd_tool` are added to automatically build, sign, and upload release artifacts to S3-compatible storage (MinIO) upon a new release. This also generates the `latest.json` file required by the updater.
- **Tauri Updater Integration:** The `tauri-plugin-updater` is integrated into the application, enabling it to check for and apply updates seamlessly.
- **Robust Git Push Handling:** The application now intelligently handles non-fast-forward push failures by prompting the user to perform a pull/merge operation before re-attempting the push.
- **Enhanced File Comparison:** A new `compare_file_to_parent` command is introduced, allowing detailed file diffs against a commit's direct parent, including the "empty tree" for initial commits.
- **Explorer Panel Improvements:** "Expand All" and "Collapse All" functionality is added to the file explorer for better navigation.

src/lib/components/ExplorerPanel.svelte

@@ -31,6 +31,8 @@
     hasRepository: boolean;
     isBusy: boolean;
     onToggleFolder: (node: ExplorerNode) => void;
+    onExpandAllFolders: () => void;
+    onCollapseAllFolders: () => void;
     onSelectNode: (node: ExplorerNode) => void;
   }
 
@@ -42,6 +44,8 @@
     hasRepository = false,
     isBusy = false,
     onToggleFolder = () => {},
+    onExpandAllFolders = () => {},
+    onCollapseAllFolders = () => {},
     onSelectNode = () => {},
   }: Props = $props();
 
@@ -152,6 +156,7 @@
 
   let explorerTree = $derived(buildExplorerTree(repoFiles));
   let visibleNodes = $derived(flattenExplorerTree(explorerTree, expandedExplorerPaths));
+  let hasFolders = $derived(explorerTree.some((node) => node.kind === "folder"));
 </script>
 
 <section class="panel grid grid-rows-[auto_1fr] overflow-hidden" aria-label="File explorer">
@@ -160,7 +165,29 @@
       <span class="eyebrow">Explorer</span>
       <h2 class="mt-0.5 text-ink text-base font-bold leading-tight">Files</h2>
     </div>
-    <span class="pill pill-count">{repoFiles.length}</span>
+    <div class="explorer-head-actions">
+      <button
+        class="explorer-bulk-button"
+        type="button"
+        onclick={onExpandAllFolders}
+        disabled={isBusy || !hasRepository || !hasFolders}
+        title="Alle Ordner aufklappen"
+        aria-label="Alle Ordner aufklappen"
+      >
+        <FolderOpen size={14} aria-hidden="true" />
+      </button>
+      <button
+        class="explorer-bulk-button"
+        type="button"
+        onclick={onCollapseAllFolders}
+        disabled={isBusy || !hasRepository || !hasFolders || expandedExplorerPaths.size === 0}
+        title="Alle Ordner zuklappen"
+        aria-label="Alle Ordner zuklappen"
+      >
+        <Folder size={14} aria-hidden="true" />
+      </button>
+      <span class="pill pill-count">{repoFiles.length}</span>
+    </div>
   </div>
 
   {#if !hasRepository}

src/lib/git.ts

@@ -128,6 +128,15 @@ export function compareFileToHead(
   return invoke<GitCommitComparison>("compare_file_to_head", { path, commit, file });
 }
 
+export function compareFileToParent(
+  path: string,
+  commit: string,
+  file: string,
+  oldFile: string | null = null,
+): Promise<GitCommitComparison> {
+  return invoke<GitCommitComparison>("compare_file_to_parent", { path, commit, file, oldFile });
+}
+
 export function searchCodeIntroductions(
   path: string,
   query: string,