fix: align git mount implementation with spec

- _checkout_branch now returns bool and falls back gracefully on failure
- Glob warning message includes matched file count
- Fix database model comment to reference remote_url
- Update tests for new branch checkout behavior

All 51 tests pass

apps/api/tests/unit/test_git_mount_resolution.py

@@ -91,23 +91,22 @@ class TestCheckoutBranch:
         assert result == "feature"
 
     def test_checkout_nonexistent_branch(self, tmp_path: Path) -> None:
-        """Test checking out a non-existent branch raises error."""
+        """Test checking out a non-existent branch returns False."""
         os.system(f"cd {tmp_path} && git init && git config user.email 'test@test.com' && git config user.name 'Test'")
         (tmp_path / "file.txt").write_text("content")
         os.system(f"cd {tmp_path} && git add . && git commit -m 'initial'")
         
-        with pytest.raises(RuntimeError, match="Failed to checkout branch"):
-            _checkout_branch(str(tmp_path), "nonexistent")
+        result = _checkout_branch(str(tmp_path), "nonexistent")
+        assert result is False
 
 
 class TestResolveSingleGitMount:
     """Unit tests for resolving a single git mount."""
 
     @pytest.mark.asyncio
-    async def test_resolve_missing_repo(self, db_session) -> None:
-        """Test that missing repo returns empty list."""
+    async def test_resolve_missing_remote_url(self, db_session) -> None:
+        """Test that missing remote_url returns empty list."""
         git_mount = {
-            "repo_id": "12345678-1234-1234-1234-123456789abc",
             "source_path": ".",
             "target_path": "/app",
         }
@@ -119,21 +118,9 @@ class TestResolveSingleGitMount:
     async def test_resolve_missing_target_path(self, db_session) -> None:
         """Test that missing target path returns empty list."""
         git_mount = {
-            "repo_id": "12345678-1234-1234-1234-123456789abc",
+            "remote_url": "https://github.com/user/repo.git",
             "source_path": ".",
         }
         
         result = await _resolve_single_git_mount(db_session, git_mount)
         assert result == []
-
-    @pytest.mark.asyncio
-    async def test_resolve_invalid_repo_id(self, db_session) -> None:
-        """Test that invalid repo_id returns empty list."""
-        git_mount = {
-            "repo_id": "not-a-uuid",
-            "source_path": ".",
-            "target_path": "/app",
-        }
-        
-        result = await _resolve_single_git_mount(db_session, git_mount)
-        assert result == []