Emit a dedicated event when upgrade state changes

[mikewheeleer]

Event on upgrade

Description

upgrade state changes are silent on-chain. This issue emits an event.

Requirements and context

• Repository scope: StableRoute-Org/Stableroute-contracts only.
• Emit a documented event whenever upgrade state changes, with the relevant fields.
• No duplicate emissions.
• Cover topic and payload in tests.

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/upgrade-92-event
• Implement changes
  • Write code in: the relevant module.
  • Write comprehensive tests in: cover the new behaviour and edge cases.
• Test and commit

Test and commit

• Run cargo fmt, cargo clippy --all-targets -- -D warnings, and cargo test.
• Cover edge cases: emitted once, payload correct.
• Include the full test output in the PR description.

Example commit message

feat(upgrade): emit state-change event

Guidelines

• Minimum 95 percent test coverage for impacted modules.
• Clear, reviewer-focused documentation.
• Timeframe: 96 hours.

Community & contribution rewards

• 💬 Join the StableRoute community on Discord: https://discord.gg/37aCpusvx
• ⭐ This is a GrantFox OSS / Official Campaign task and may be rewarded. When your PR is merged you'll be prompted to rate the project — a 5-star rating is much appreciated.

[greatest0fallt1me]

Hello Maintainers 👋,
I’m interested in picking up this issue and contributing to the project.
I have solid experience working across both frontend and blockchain layers, including building user interfaces with Next.js and developing Stellar smart contracts using Rust (Soroban). I’m familiar with translating Figma designs into pixel-accurate UIs, handling wallet integrations, and writing efficient, well-tested contract logic.
I focus on writing clean, maintainable code, following repository standards, and keeping communication transparent throughout the development process. I can start immediately and complete the work within the expected timeframe.
Excited to collaborate and add value to the project 🚀
Thank you!