Add branch creation and file history search

Implement the ability to create new local branches directly from the application's UI. This includes a new backend command to handle branch creation with validation and a frontend form in the branch panel.

Additionally, extend the global search dialog to include a "Files" tab. Users can now search for files by name or path within the repository. Selecting a file in the search results displays its full commit history, with options to diff the file at a specific commit or restore it to that version.

src/lib/git.ts

@@ -27,6 +27,10 @@ export function checkoutBranch(path: string, branch: string): Promise<GitStatus>
   return invoke<GitStatus>("checkout_branch", { path, branch });
 }
 
+export function createBranch(path: string, branch: string): Promise<GitStatus> {
+  return invoke<GitStatus>("create_branch", { path, branch });
+}
+
 export function stageFiles(path: string, files: string[]): Promise<GitStatus> {
   return invoke<GitStatus>("stage_files", { path, files });
 }