fix: remove branch type assertion from detectGit repo test

The "detects a git repository" test should only assert isRepo.
Branch validation is handled by the dedicated branch test which
accounts for CI detached HEAD returning undefined.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: anandgupta42

packages/altimate-code/test/tool/project-scan.test.ts

@@ -45,7 +45,6 @@ describe("detectGit", () => {
   test("detects a git repository in the current repo", async () => {
     const result = await detectGit()
     expect(result.isRepo).toBe(true)
-    expect(typeof result.branch).toBe("string")
   })
 
   test("branch is a non-empty string or undefined (detached HEAD)", async () => {