Fixes WOOMOB-1333

Description

This PR refactors the POSCatalogSyncCoordinator to ensure consistency between full and incremental sync interface and implementations by introducing private shouldPerform*Sync helper methods for both sync types.

Discussion ref: #16117 (comment)

Key Changes:

• Added private shouldPerformFullSync method to encapsulate sync decision logic for full syncs
• Made shouldPerformIncrementalSync private and consistent with full sync pattern
• Updated both performFullSyncIfApplicable and performIncrementalSyncIfApplicable to accept maxAge and forceSync parameters
• Removed maxIncrementalSyncAge property in favor of passing maxAge as a parameter
• Added protocol extension with convenience methods performFullSync and performIncrementalSync that call the main methods with default parameters
• Both sync methods now have consistent parameter signatures: siteID, maxAge, and forceSync

Benefits:

• Consistent API surface between full and incremental sync operations
• Better encapsulation of sync decision logic
• More flexible for future analytics or UI integration (methods can be made public if needed)
• Clearer separation between sync execution and sync decision logic

Steps to reproduce

Local Catalog is behind a local feature flag enabled in debug builds. No behavior changes are expected, a confidence testing would be helpful:

• Launch the app in a store eligible for POS with catalog size <= 1000 --> observe the POSCatalogSyncCoordinator messages in the console, they should match the full sync status
• Tap on the POS tab
• Go to POS settings > Catalog --> the sync info should be up-to-date
• Tap Refresh catalog to trigger a full sync --> after the full sync, the sync info should be up-to-date

Testing information

I tested for POS stores in iPad A16 iOS 26.0 simulator:

• Catalog size <= 1000, no previous full sync
• Catalog size <= 1000, force full sync
• Catalog size <= 1000, previous full sync
• Catalog size > 1000 --> skipped

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.