fix(backtest): preserve missing quote integrity in research simulators

[Pigbibi]

Scope

• F3 / RA-10: preserve raw missing quotes in ordinary backtest matrices, including all-missing observed dates and assets.
• Reuse held/targeted price checks; validate the two required prices for active Russell/DCA proxy sleeves. Zero-weight and zero-exposure sleeves remain allowed.
• No live signal changes, dependency/lock changes, provider calls, real replay, or historical artifact replacement.

Offline synthetic validation

• Existing ETF baseline: 33 passed.
• RED: 5 ETF failures; 4 proxy subtest failures on old consumer behavior.
• Raw-matrix full regression: 672 passed / 350 subtests; SOXL/WFA: 15 passed.
• Final ETF/combo targeted: 44 passed / 6 subtests; final combo/orchestrator: 14 passed / 9 subtests.
• Full Ruff, pip check (18 packages), diff and scope checks passed. Locked offline environment uses actual QPK c812ed70; pytest and calendar test tools match CI requirements.
• Missing pandas_market_calendars initially prevented two test modules from collecting; installed existing CI test dependency offline, then those tests passed.

Limits

Corrected missing-price behavior may reject historical incomplete inputs. No old results were regenerated; this is not promotion or strategy performance evidence.