Add GPTRequirementWriter browser operator

[lisihao]

Summary

• add a dedicated browser-agent-backed GPTRequirementWriter operator
• enforce raw/original requirement priority over upstream rewritten prompt input
• wire logical operator, physical operator, actor, registry, and schedule entries
• add focused tests for Thinking High proof and raw requirement source precedence

Verification

• python3 -m py_compile harness/tools/chatgpt_requirement_writer_operator.py harness/tests/test_chatgpt_requirement_writer_operator.py
• pytest -q harness/tests/test_chatgpt_requirement_writer_operator.py
• pytest -q harness/tests/test_chatgpt_requirement_writer_operator.py harness/tests/test_chatgpt_report_operator.py harness/tests/test_logical_operator_schema.py
• python3 contract self-check for GPTRequirementWriter config wiring
• git diff --check

Notes

• provider/physical full-suite failures are pre-existing on the current base branch and were reproed separately on a detached worktree from origin/codex/capsule-proof-adapter-runtime.