test: pin real offline producer-to-receiver contracts

[Pigbibi]

Scope

• Execute exact upstream IBKR and Schwab projection + strip functions using synthetic reports; verify source revision and file digest, forbid network/subprocess calls during projection.
• Exercise authenticated receiver, local SQLite, read model/history, identity rejection and newer stripped payloads without production changes.
• Add independent offline CI and bilingual evidence/runbook. No runtime dependencies, deployment paths, publisher changes or live data.

Important uncovered blocker (not fixed)

Current stripped payloads work for both platforms. IBKR pre-strip archive holdings work as a future-publication contract (stocks_only). Schwab pre-strip archive rows add currency_source: owner_confirmed, which QRS exact-key positions validation rejects with HTTP 400 invalid_account_facts_positions. The negative contract explicitly preserves this blocker. Green CI does NOT authorize Schwab holdings publication. A separately approved producer mapping or explicit receiver provenance contract is needed.

Evidence

• IBKR pinned bd5c1a12d9cd0df8dbd88c1eb8b058b7b849990f; Schwab pinned 5b563ad3609eefd9cf431ead82d0f30c586645db.
• Local new roundtrip and existing account_facts suite passed.
• Deterministic generation matched byte-for-byte; config/runtime validation and actionlint passed.
• Python suite: 543 tests, 10 existing skips.
• Independent review: no actionable findings; repeated generation and roundtrip passed.
• Exact remote tree verified equal to locally tested tree. Final-head CI passed for 23210104742c58d26e19937f33ffe7545250b481: Validate (Python, JS, actionlint) and Offline producer receiver contracts.

See docs/producer-receiver-contract.md. Draft only; no merge, deploy or publisher activation.