Implement Payroll Run Input Locking & Snapshot Mechanism to Prevent Concurrent Data Corruption

[revatikadam0607]

Problem

When payroll runs are being calculated, employee, attendance, leave, and compensation data
can be modified. This causes the payroll to be based on inconsistent input states—silently
producing wrong results.

Solution

Implement a controlled locking mechanism:

• Lock input data when payroll run starts
• Capture snapshot of required inputs
• Prevent conflicting modifications during calculation
• Release locks safely on completion or failure
• Maintain version reference in finalized payroll

Key Features

✅ Input boundary definition (lock start time)
✅ Record-level locking (employee, attendance, leave, compensation)
✅ Snapshot capture for audit trail
✅ Concurrent run prevention
✅ Safe lock release on failure
✅ Version tracking in payroll records
✅ Tests for concurrent data updates

Acceptance Criteria

✅ Payroll run has defined input boundary
✅ Source data cannot silently modify active calculation
✅ Concurrent runs cannot corrupt employee data
✅ Finalized payroll references input version
✅ Failed runs release locks safely
✅ Tests cover concurrent scenarios

Closes#1991
@Dev1822

[vercel]

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