fix: use full git log in merge tests to match trailer-based milestone IDs

Tests were checking `git log --oneline` for M001, but the refactor moved
milestone IDs from commit subject scopes to git trailers in the body.
Switch to `git log` (full format) so the trailer content is visible.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/gsd/tests/all-milestones-complete-merge.test.ts

@@ -183,8 +183,8 @@ test("single milestone worktree is merged to main when all complete (#962)", (t)
     "milestone branch should be deleted",
   );
 
-  // Verify squash commit on main
-  const log = run("git log --oneline -3", tempDir);
+  // Verify squash commit on main (milestone ID is in trailer, not subject)
+  const log = run("git log -3", tempDir);
   assert.ok(
     log.includes("M001"),
     "squash commit on main should reference M001",

src/resources/extensions/gsd/tests/milestone-transition-worktree.test.ts

@@ -94,8 +94,8 @@ test("worktree swap on milestone transition: merge old, create new", () => {
     assert.equal(process.cwd(), tempDir, "cwd restored to project root after merge");
     assert.ok(!isInAutoWorktree(tempDir), "no longer in auto-worktree after merge");
 
-    // Verify M001 work was merged to main
-    const mainLog = run("git log --oneline -3", tempDir);
+    // Verify M001 work was merged to main (milestone ID is in trailer, not subject)
+    const mainLog = run("git log -3", tempDir);
     assert.ok(mainLog.includes("M001"), "M001 squash commit should be on main");
 
     // Phase 3: Create new worktree for M002 (simulates new milestone)