aisman

Session 155, Step 1: Credit provider cost recording prompt dialog in Wf S4
- AIM-2903 Credit provider cost recording prompt dialog in Wf S4
- AIM-2904 Skip remaining credit dialog when doNotUpdateRemainingCredit is true
- AIM-2905 Server-side import API handling for doNotUpdateRemainingCredit

Outcome:
Implemented all three issues:

- **AIM-3504**: Added `_findSiblingTasksWithSameProvider`, `_showCostRecordingPrompt`, and `_saveS4CostToEarlierTask` functions. The cost recording prompt appears when clicking "Update remaining credit" and a sibling task uses the same credit provider. Dialog includes calculated cost, red-highlighted override input with diff display, "I want to override" checkbox, "Recalculate" link, and "No, I'll set it manually" checkbox.
- **AIM-3505**: Modified `_processS4TaskWithCreditCore` to check `step.doNotUpdateRemainingCredit` in the output file. When true, skips the credit dialog and shows an info toast with the pre-recorded cost.
- **AIM-3506**: Added `DoNotUpdateRemainingCredit` property to `AgentStepOutput` and an early-return guard in `UpdateCreditProviderRemainingAsync` that skips credit provider/purchase table updates when the flag is true.