Recover first-frame Binance ladder input rollback

[jackhai9]

Root cause

Binance can restore a controlled ladder quantity input in a microtask after the userscript write returns but before the first animation-frame observation. Version 2.7.136 preserved recovery only for synchronous rejection or rollback after at least one observed matching frame, leaving this first-frame window uncovered. A natural Open Long reproduction confirmed the same empty controlled value with no diagnostic probe active.

Changes

• preserve the pre-write value as an opt-in provisional rollback contract
• recover only when the same input returns to that exact value before settling
• cancel recovery for any different non-empty user or page value
• retain the shared bounded per-input write budget
• enable the new contract only for ladder synchronization
• bump the userscript version to 2.7.137

Validation

• npm test (371/371)
• npm run build:binance-orderbook-trade
• npm run check:binance-orderbook-trade
• git diff --check
• focused trade-form/source regression tests (78/78)
• independent read-only root-cause and final-diff reviews