fix: preserve legacy IBKR cycle results without release receipts

[Pigbibi]

Legacy IBKR runtime targets have no strategy release identity. After a strategy cycle returned, the unconditional execution-receipt attachment rejected the missing revision, returned HTTP 500, and prevented the execution summary and reconciliation artifact path from being finalized.

Skip the optional receipt only when the runtime report explicitly identifies a legacy, unattested target with no release identity. Preserve the missing-evidence state and the original cycle result, including business failures. Attested invalid revisions and missing attestation still fail validation; broker execution, risk checks, dependency pins, and deployment configuration are unchanged.

Validation:

• Four real-handler regression cases reproduced HTTP 500 before the fix, covering both affected profiles and successful/blocked results.
• Focused request/receipt suite: 66 passed.
• Full repository suite: 633 passed, 5 skipped.
• Ruff, production startup validation, pinned-dependency consistency, lockfile check, and diff check passed.
• Read-only deployment preflight passed for the five configured services, with no planned enablement, strategy-profile, dry-run, or force-run changes.

The handler regressions use an offline cycle double while retaining the actual report builder, receipt adapter, and HTTP handler. No live trading endpoint was invoked.