feat: scheduling, and cross-network testing

[NanaKhadija1980j]

PR Overview

Summary

Implement scheduled notification delivery and cross-network compatibility testing to improve notification reliability, deployment consistency, and contract behavior across all supported blockchain networks.

Description

This PR enhances NotifyChain by introducing scheduled notification delivery, allowing organizations to automate future notifications, and by adding comprehensive cross-network compatibility testing to ensure consistent smart contract behavior across supported blockchain environments.

Changes Included

Notification Scheduling

• Designed notification scheduling schema
• Added scheduling APIs
• Implemented background processing for scheduled delivery
• Added timezone conversion support
• Added automated tests covering scheduling scenarios and edge cases
• Logged failed scheduling attempts

Cross-Network Compatibility Testing

• Added network-specific test configurations
• Implemented deployment validation across supported blockchain networks
• Verified event emissions remain consistent
• Compared contract behavior between networks
• Added automatic compatibility report generation

Acceptance Criteria Covered

Notification Scheduling

• ✅ Scheduled notifications delivered at the correct time
• ✅ Timezone conversions handled correctly
• ✅ Failed schedules logged
• ✅ Automated tests cover common and edge-case scenarios

Cross-Network Compatibility Testing

• ✅ Tests pass across supported blockchain networks
• ✅ Event emissions remain consistent
• ✅ Compatibility reports generated automatically

Closes #217
Closes #223