refactor: Remove write_protected from user-facing SDK API and add GraphQL examples

Changes:
- Remove write_protected parameter from Experiment.__init__() and RemoteClient.create_or_update_experiment()
- Hardcode write_protected to False internally (kept for internal validation checks)
- Update API Reference documentation to reflect parameter removal
- Add comprehensive GraphQL projectTree query examples (Python, curl, JavaScript)
- Add GraphQL_ProjectTree_Examples.md documentation with complete examples

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

Author: tomtao57