feat(git): add ignore and untrack paths commands

The changes introduce server-side commands to manage gitignore
 rules and to untrack paths without deleting local files.
 A new GitIgnoreKind enum and helper functions normalize targets
 and build proper ignore patterns, and UI code was wired to use
 these commands.

- add_to_gitignore command and related helpers
- untrack_paths command to remove paths from the index
- UI wiring to expose ignore and untrack actions in explorer

src-tauri/src/main.rs

@@ -10,8 +10,8 @@ use external_tools::{
     detect_external_tools, launch_external_diff, launch_external_merge, launch_external_tool,
 };
 use git::{
-    SearchCancellationState, add_remote, add_worktree, amend_commit, apply_file_patch,
-    cancel_code_search, cancel_file_history, checkout_branch, cherry_pick_abort,
+    SearchCancellationState, add_remote, add_to_gitignore, add_worktree, amend_commit,
+    apply_file_patch, cancel_code_search, cancel_file_history, checkout_branch, cherry_pick_abort,
     cherry_pick_commit, cherry_pick_continue, clone_repository, commit, commit_ai_generate,
     commit_ai_load, commit_ai_local_models, commit_ai_review, commit_ai_split, commit_ai_status,
     compare_commits, compare_file_to_head, compare_file_to_parent, create_branch, create_tag,
@@ -30,7 +30,7 @@ use git::{
     revert_commit, run_sequence_editor_if_requested, search_code_introductions,
     set_branch_upstream, set_commit_note, stage_files, start_interactive_rebase, stash_apply,
     stash_drop, stash_pop, stash_push, undo_last_commit, unlock_worktree, unstage_files,
-    update_remote,
+    untrack_paths, update_remote,
 };
 use std::path::{Path, PathBuf};
 use std::sync::Mutex;
@@ -254,6 +254,8 @@ async fn main() {
             cherry_pick_abort,
             stage_files,
             unstage_files,
+            add_to_gitignore,
+            untrack_paths,
             stash_push,
             stash_apply,
             stash_pop,