fix: support exact readonly account-facts publication

[Pigbibi]

Changes

• Archive account facts from the existing readonly probe snapshot after the configured single account selector matches.
• Allow an exact UTC report filename for the existing protected account-facts publisher.
• Skip the heartbeat job only for an explicit single-report funds publication. Scheduled and ordinary manual behavior remain unchanged.

Validation

• Readonly probe regression tests: 14 passed.
• Publisher tests: 36 passed.
• Ruff, actionlint and diff checks passed.
• Source-only fixtures use unrelated placeholder identities. Runtime bindings and credentials remain in protected storage.

The readonly probe does not use the strategy market gate. This change does not alter trading, risk limits or production schedules.