feat: publish bounded Firstrade execution receipts

[Pigbibi]

Summary

• derive a bounded execution receipt from Firstrade’s persisted strategy run stage
• preserve uncertainty for an escaped runtime exception rather than claim no broker activity
• advance the shared runtime-evidence publisher and QPK pin

Safety

• submitted orders remain submitted/not_observed; this code never infers an acknowledgement or fill
• no strategy sizing, order routing, broker configuration, or execution permission changed

Verification

• PYTHONPATH=/home/ubuntu/Projects/.worktrees/qpk-execution-receipt/src:. python3 -m unittest tests.test_execution_receipt_adapter -v
• python3 scripts/check_qpk_pin_consistency.py --pin-file /home/ubuntu/Projects/.worktrees/qpk-execution-receipt/QPK_PIN --paths pyproject.toml uv.lock qsl.toml