feat: add event schema compatibility testing foundation

[coderolisa]

• Add historical event fixtures for schema version 1
• Create compatibility tests to validate event structures
• Implement tests for breaking change detection
• Add documentation for compatibility testing approach

This establishes the foundation (2%) for ensuring changes to event structures don't unintentionally break listener decoders or external consumers.

Fixtures cover 5 critical events:

• NotificationScheduled
• NotificationRevoked
• NotificationExpired
• AutoshareCreated
• BatchNotificationsCreated

Tests verify:

• Schema compatibility between contract and consumer
• Historical fixture structure validity
• Breaking change detection mechanisms

Overview

Related Issue

Closes #1031

Changes

Verification

# e.g.
cd dashboard && npm test
cd listener && npm run typecheck && npm test
cd contract/contracts/hello-world && cargo test

How to Test

Checklist

• Branch is up to date with main
• Tests added/updated and all pass locally
• cargo fmt --all run (if Rust changes)
• npm run lint passes (if TypeScript changes)
• Documentation updated if behavior changed

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@coderolisa Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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