fix: bind paper commands to their runtime scope

[Pigbibi]

Summary

• require every shared paper-command consumer to supply its runtime-owned platform, account scope, and strategy-profile binding
• reject a mismatched command before platform reconciliation, with precise fail-closed gate findings
• preserve release, paper-risk, and create-only lifecycle checks
• document the additional consumer boundary and add regression coverage

Verification

• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 PYTHONPATH=src python -m pytest -q tests/test_paper_execution_command_consumer.py tests/test_paper_execution_admission.py tests/test_execution_commands.py tests/test_runtime_command_gate.py
• PYTHONPATH=src python -m compileall -q src tests/test_paper_execution_command_consumer.py
• git diff --check

No broker SDK, execution port, deployment, or live-mode path is introduced.