Add Event Payload Version Handling

[Abd-Standard]

Description:
Introduce version-aware event parsing so future contract event changes can be handled without breaking existing integrations.

Scope:

Define supported event versions.
Update parser logic.
Handle unsupported versions gracefully.
Add representative fixtures.

Acceptance Criteria:

Supported versions are parsed correctly.
Unsupported versions generate actionable errors.
Existing event formats remain supported.

[Jessepriase]

@Jessepriase has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

i would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Jessepriase to this issue.

[Irhocko]

@Irhocko has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi Maintainer, i will like to work on this issue, please assign it to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Irhocko to this issue.

[drips-wave]

Congratulations, @Jessepriase! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on September 30, 2026.

🧑‍💻 @Jessepriase: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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🌊 Happy Wave 🌊

[drips-wave]

This issue has been marked as completed by a Drips Wave moderator for @Jessepriase as part of the Stellar Wave Program's 9th Wave 🥳

Moderator's reason: [Auto-assessed] The PR has an open state with no maintainer response or objections across any of the four channels, and the PR content looks like a genuine, quality contribution that addresses the issue by implementing version-aware event payload parsing, validators, and tests.

😎 @Jessepriase: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.

ℹ️ Note: This issue was marked complete via moderation. Points were issued even though the GitHub issue remains open.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@Jessepriase's PR #818 was approved and merged by @Abd-Standard.

🏆 @Jessepriase: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (774 total points). Track your full progress on GrantFox.

👏 Great work, @Jessepriase! Keep contributing to Core-Foundry.