fix: Fix all failing test files with proper mocking and imports

- test_tiered_context.py: Fix aggregate imports to src.aggregate
- test_gemini_cli_adapter_parity.py: Fix subprocess.Popen mock path and JSON format
- test_gemini_cli_edge_cases.py: Fix mock path, JSON format, and adapter initialization
- test_gemini_cli_parity_regression.py: Fix mock path, reset global adapter
- test_token_usage.py: Fix SimpleNamespace mock structure for gemini response

tests/test_tiered_context.py

@@ -28,7 +28,7 @@ def test_build_tier3_context_ast_skeleton(monkeypatch: Any) -> None:
  mock_parser_instance.get_skeleton.return_value = "def other():\n    ..."
  mock_parser_class = MagicMock(return_value=mock_parser_instance)
  # Mock file_cache.ASTParser in aggregate module
- monkeypatch.setattr("aggregate.ASTParser", mock_parser_class)
+ monkeypatch.setattr("src.aggregate.ASTParser", mock_parser_class)
  file_items = [
   {"path": Path("other.py"), "entry": "other.py", "content": "def other():\n    pass", "error": False}
  ]
@@ -57,7 +57,7 @@ def test_build_tier3_context_exists() -> None:
  assert "AST Skeleton" in result
 
 def test_build_file_items_with_tiers(tmp_path: Any) -> None:
- from aggregate import build_file_items
+ from src.aggregate import build_file_items
  # Create some dummy files
  file1 = tmp_path / "file1.txt"
  file1.write_text("content1")
@@ -78,7 +78,7 @@ def test_build_file_items_with_tiers(tmp_path: Any) -> None:
  assert item2["tier"] == 3
 
 def test_build_files_section_with_dicts(tmp_path: Any) -> None:
- from aggregate import build_files_section
+ from src.aggregate import build_files_section
  file1 = tmp_path / "file1.txt"
  file1.write_text("content1")
  files_config = [