Optimize repository loading and enhance Git UI

Consolidate multiple Git backend calls into a single bundle to reduce
overhead when opening and auto-refreshing repositories. This significantly
improves performance by fetching status, branches, commits, and files
in one optimized operation, instead of re-running 'git rev-parse' and
'git status' multiple times.

Also, streamline commit history loading by fetching file changes inline
via 'git log --name-status -z', eliminating expensive per-commit
'git diff-tree' processes.

Additionally, introduce the ability to create new branches from a
specific commit in the history and refactor the commit comparison
feature into a dedicated dialog. The status panel now displays concise
file names.

src/lib/types.ts

@@ -54,6 +54,13 @@ export interface GitRepositoryFile {
   status: FileStatusKind | null;
 }
 
+export interface RepositoryBundle {
+  status: GitStatus;
+  branches: GitBranch[];
+  commits: GitCommit[];
+  files: GitRepositoryFile[];
+}
+
 export interface GitDiffFile {
   path: string;
   old_path: string | null;