[HARD][SOROBAN GOVERNANCE] Add timelocked, quorum-approved WASM upgrades with schema migration guards

[Obiajulu-gif]

Summary

The design documents call for upgradeable contracts and governed production releases, but the contracts expose no controlled WASM upgrade or schema-migration entrypoint.

Repository evidence

• docs/stellar-asset-and-soroban-design.md describes Mainnet upgradeability, quorum approval, and timelocks.
• The Soroban contracts do not expose an authorized update_current_contract_wasm path or persisted schema version.

Scope

• Add proposal, approval, timelock, execution, and cancellation states for upgrades.
• Persist code/schema versions and require an explicit migration plan before activation.
• Emit auditable proposal and execution events.

Acceptance criteria

• No single signer can upgrade immediately.
• Execution is impossible before quorum and timelock conditions are met.
• Incompatible schema versions fail before changing the active WASM.

Tests

• Authorization, quorum, expiry, cancellation, and replay tests.
• Upgrade fixture proving state survives a supported migration and rejects an incompatible one.

Non-goals

• Choosing a specific multisig vendor or deploying an upgrade to Mainnet.

[BigDella]

i will love to work on this issue

[grantfox-oss]

🦊 GrantFox — @BigDella has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #164)
2. Your PR will be reviewed by the Chainmove maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

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

@BigDella's PR #211 was approved and merged by @Obiajulu-gif.

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👏 Great work, @BigDella! Keep contributing to Chainmove.