Add structured lifecycle events for governance

[greatest0fallt1me]

Description

This is a smart-contract issue for the GrantFox FWC26 campaign (Stellar Wave). Emit stable, structured events on governance lifecycle changes for off-chain indexers.

Requirements and Context

• Implement per the description above
• Add focused tests for the change
• Document any API/visible changes
• Adhere to repo's lint and code style
• Must be secure, tested, and documented

Suggested Execution

1. Fork the repo and create a branch
2. Implement changes:
   • contracts/governance/src/events.rs
3. Test and commit; open a PR with Closes #981 in the body

Guidelines

• Minimum 95% test coverage with cargo test
• require_auth on every state-changing entrypoint
• Overflow-safe math; no unwrap() in production paths
• Clear NatSpec-style /// rustdoc
• Timeframe: 96 hours

[chi797]

@chi797 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Good day maintainer
Kindly assign me this issue please

ℹ️ Repo Maintainers: To accept this application, review their application or assign @chi797 to this issue.

[datagerl]

@datagerl has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hey maintainer can I please work on this issue

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

[frank0277]

@frank0277 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi maintainer please I would like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @frank0277 to this issue.

[drips-wave]

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

🧑‍💻 @datagerl: 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

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[greatest0fallt1me]

You've got this one, @datagerl. Discord community: https://discord.gg/WC53JxDqx

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@datagerl's PR #1035 was approved and merged by @greatest0fallt1me.

🏆 @datagerl: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (277 total points). Track your full progress on GrantFox.

👏 Great work, @datagerl! Keep contributing to Predictify-org.