feat(git): add tag management and cherry-pick workflow

This update extends the Git backend and UI to support listing,
creating, deleting, and pushing tags. It also adds cherry-pick
commands with proper in-progress detection and conflict handling, and
prevents other operations while a cherry-pick is active.

- Add GitTag model, tag listing, and tag CRUD/push commands
- Implement cherry-pick start/continue/abort with status tracking
- Update UI to display tags and gate actions during cherry-pick

src/lib/git.ts

@@ -12,6 +12,7 @@ import type {
   GitSearchHit,
   GitStash,
   GitStatus,
+  GitTag,
   LocalModelOption,
   PatchApplyAction,
   RepositoryBundle,
@@ -94,6 +95,49 @@ export function deleteBranch(path: string, branch: string, force = false): Promi
   return invoke<GitStatus>("delete_branch", { path, branch, force });
 }
 
+export function listTags(path: string): Promise<GitTag[]> {
+  return invoke<GitTag[]>("list_tags", { path });
+}
+
+export function createTag(
+  path: string,
+  name: string,
+  target?: string,
+  message?: string,
+): Promise<GitTag[]> {
+  return invoke<GitTag[]>("create_tag", {
+    path,
+    name,
+    target: target?.trim() ? target.trim() : null,
+    message: message?.trim() ? message.trim() : null,
+  });
+}
+
+export function deleteTag(path: string, name: string): Promise<GitTag[]> {
+  return invoke<GitTag[]>("delete_tag", { path, name });
+}
+
+export function pushTag(
+  path: string,
+  name: string,
+  username?: string,
+  password?: string,
+): Promise<void> {
+  return invoke<void>("push_tag", { path, name, username: username ?? null, password: password ?? null });
+}
+
+export function cherryPickCommit(path: string, commit: string): Promise<GitStatus> {
+  return invoke<GitStatus>("cherry_pick_commit", { path, commit });
+}
+
+export function cherryPickContinue(path: string): Promise<GitStatus> {
+  return invoke<GitStatus>("cherry_pick_continue", { path });
+}
+
+export function cherryPickAbort(path: string): Promise<GitStatus> {
+  return invoke<GitStatus>("cherry_pick_abort", { path });
+}
+
 export function stageFiles(path: string, files: string[]): Promise<GitStatus> {
   return invoke<GitStatus>("stage_files", { path, files });
 }