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/app.css

@@ -593,6 +593,23 @@
 
   /* --- Explorer --- */
 
+  .explorer-head-actions { display: flex; align-items: center; gap: 5px; flex: 0 0 auto; }
+  .explorer-bulk-button {
+    width: 26px;
+    min-width: 26px;
+    min-height: 26px;
+    padding: 0;
+    border-color: rgba(65,209,255,0.2);
+    border-radius: 7px;
+    color: var(--color-ink-dim);
+    background: rgba(65,209,255,0.06);
+  }
+  .explorer-bulk-button:hover:not(:disabled) {
+    border-color: rgba(65,209,255,0.45);
+    color: #ffffff;
+    background: rgba(65,209,255,0.13);
+  }
+
   .explorer-row {
     display: grid;
     grid-template-columns: auto auto minmax(0, 1fr) auto;