test: restore node tests without document operations

Restored comprehensive tests for:
- ConditionNode (32 tests)
- SetVariableNode (8 tests)
- LogNode (8 tests)
- DelayNode (7 tests)
- Node utility functions (17 tests)

Document-related tests (TestHazelNode, TestCreateDocumentNode,
TestUpdateDocumentNode) temporarily excluded to identify failures.

Author: claude