fix(contracts): align official backtest request fixture

[hjcud]

What changed

• vendored the backend-owned OFFICIAL_BACKTEST_REQUESTED valid fixture byte-for-byte
• required all nine provider runtime fields in the consumer schema and contract tests
• made BASIC dispatch verify the request period, dataset hash, and feature materialization pins against the provider-created run
• aligned lifecycle/API test harness identities with the provider-registered run and execution policy

Why

Launch-readiness task 3.4 requires the backtest consumer fixture to match the backend producer fixture exactly. The consumer copy was missing nine runtime fields, and BASIC dispatch was substituting stored values for several message fields instead of checking provider/consumer run identity.

Impact

The backtest engine now rejects incomplete official requests and detects BASIC run identity drift before publishing a job. This unblocks the root parity gate and downstream INT01 once this PR is merged and the root submodule pointer is advanced by the root owner.

Validation

• python -m pytest -q — passed (3 skipped)
• ruff check . — passed
• producer and consumer fixture Git blob hashes both 1b754da1a507d64f0479361588dd0636c23d4fec
• git diff --cached --check — passed