fix: persist edited regular hours when adding overtime in RRoP edit employee

[serikjensen]

What

Fixes a bug in the RRoP UNSTABLE_PayrollEditEmployee flow (via usePayrollEditEmployeeForm): editing an hourly employee's regular hours and then clicking Add overtime reverted the edited value back to the server total (e.g. an edited 32 snapped back to 40).

Why

actions.addOvertime re-derived the form defaults from the prepared payroll (the API), then setValue'd each line's first workweek cell to that API total, clobbering whatever the user had just typed into the collapsed input. On top of that, flipping the internal withOvertime flag recomputes resolvedDefaults, which feeds useForm's values prop and resets the form (keeping only dirty fields).

Fix

• Overlay the live collapsed value onto the first workweek cell when revealing the split, instead of using the API total.
• Mark the seeded values dirty (shouldDirty: true) so the values-prop reset preserves them via keepDirtyValues rather than reverting to the API value.

Tests

Added a regression test: edit collapsed Regular Hours to 32, call addOvertime, and assert the first workweek cell holds 32 (not the API total 40). All 28 hook tests pass.

Reviewer notes

• Only affects the RRoP edit-employee hook, gated behind the payrollRegularRateOfPay unstable flag.
• No API/wire-format changes.

Screen.Recording.2026-09-11.at.3.06.15.PM.mov

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