feat(git): Add comprehensive worktree management capabilities

This update introduces full support for Git worktrees, allowing users to manage multiple isolated working copies within a single repository. This includes new functionality to list, add, remove, move, lock, and repair worktrees, significantly enhancing the repository's capability to handle parallel development streams.

- Added `GitWorktree` structure definition across API contracts and Rust backend
- Implemented full CRUD operations for worktrees in Tauri commands
- Updated UI components (App.svelte, BranchPanel.svelte) to expose worktree management dialog

src/lib/components/BranchPanel.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { Check, ChevronDown, ChevronRight, Folder, FolderOpen, GitBranch, GitMerge, Pencil, Plus, Tag as TagIcon, Trash2, Upload, X } from "@lucide/svelte";
+  import { Check, ChevronDown, ChevronRight, Folder, FolderOpen, GitBranch, GitMerge, HardDrive, Pencil, Plus, Tag as TagIcon, Trash2, Upload, X } from "@lucide/svelte";
   import type { GitBranch as GitBranchInfo, GitTag } from "../types";
 
   type BranchTreeNode = BranchFolderNode | BranchLeafNode;
@@ -58,6 +58,8 @@
     onCreateTag: (name: string, message: string) => void | Promise<void>;
     onDeleteTag: (tag: GitTag) => void | Promise<void>;
     onPushTag: (tag: GitTag) => void | Promise<void>;
+    onManageWorktrees: () => void;
+    onCreateWorktree: (branch: GitBranchInfo) => void | Promise<void>;
     collapsed?: boolean;
     onToggleCollapsed?: () => void;
   }
@@ -79,6 +81,8 @@
     onCreateTag = () => {},
     onDeleteTag = () => {},
     onPushTag = () => {},
+    onManageWorktrees = () => {},
+    onCreateWorktree = () => {},
     collapsed = false,
     onToggleCollapsed = () => {},
   }: Props = $props();
@@ -271,6 +275,13 @@
     if (branch.remote) await onDeleteRemoteBranch(branch); else await onDeleteBranch(branch);
   }
 
+  async function createContextWorktree() {
+    const branch = contextBranch;
+    closeBranchContextMenu();
+    if (!branch) return;
+    await onCreateWorktree(branch);
+  }
+
   async function checkoutContextBranch() {
     const branch = contextBranch;
     if (!branch || branch.current || isBusy) return;
@@ -368,6 +379,16 @@
       <h2 class="mt-0.5 text-ink text-base font-bold leading-tight">Refs</h2>
     </div>
     <div class="branch-head-actions">
+      <button
+        class="branch-create-toggle"
+        type="button"
+        onclick={onManageWorktrees}
+        disabled={!hasRepository || isBusy}
+        title="Manage worktrees"
+        aria-label="Manage worktrees"
+      >
+        <HardDrive size={14} aria-hidden="true" />
+      </button>
       <button
         class="branch-create-toggle"
         type="button"
@@ -661,6 +682,10 @@
         <GitBranch size={14} aria-hidden="true" />
         Rebase current onto this
       </button>
+      <button type="button" role="menuitem" onclick={createContextWorktree} disabled={isBusy || contextBranch.remote || contextBranch.current}>
+        <HardDrive size={14} aria-hidden="true" />
+        Open in new worktree
+      </button>
       <div class="menu-separator" role="separator"></div>
       <button type="button" role="menuitem" onclick={renameContextBranch} disabled={isBusy || contextBranch.remote}>
         <Pencil size={14} aria-hidden="true" />