[CO-06] Add permission separation and audit trail to restaurant_registry admin operations

[Leothosine]

Problem

contracts/restaurant_registry/src/lib.rs:141-176 - set_active() allows either the admin or the restaurant owner to activate/deactivate any restaurant, with no audit trail of who performed the action. A compromised admin key can silently deactivate every restaurant on the platform. There is no distinction between an owner voluntarily closing their restaurant and an admin suspending it.

Proposed Solution

1. Add deactivated_by: Option<Address> and deactivated_at: Option<u64> to the Restaurant struct
2. Split set_active() into:
   • owner_close_restaurant(env, caller, restaurant_id) - owner-only, permanent closure
   • admin_suspend_restaurant(env, caller, restaurant_id, reason: Symbol) - admin-only, recoverable
   • admin_unsuspend_restaurant(env, caller, restaurant_id) - admin-only
3. Emit events including caller: (symbol_short!("rest"), symbol_short!("suspend"), restaurant_id, caller, timestamp)

Acceptance Criteria

• Restaurant owner cannot call admin_suspend_restaurant() (panics with unauthorized)
• Admin can suspend and unsuspend any restaurant
• Admin cannot call owner_close_restaurant() for a restaurant they don't own
• All events include the caller address and ledger timestamp
• Unit tests cover all four actor/action permutations

[Menjay7]

Hi! I came across this issue and would love to work on it. I have experience with similar tasks and I'm confident I can investigate, implement a clean solution, and thoroughly test it before submitting a PR. If the issue is still open, I would appreciate it if you could assign it to me. Thank you!

[Senorespecial]

I would really like to work on this issue, please assign.

[Senorespecial]

I would really like to work on this issue, please assign.

[devwums]

Hello team, i would love to resolve this issue. i have so many free time so i will be dedicated to your project. I am a software engineer and web3 developer. I will surely deliver on this with a quality pr.

[grantfox-oss]

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

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #284)
2. Your PR will be reviewed by the tosirano maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

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

@devwums's PR #295 was approved and merged by @Leothosine.

🏆 @devwums: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (296 total points). Track your full progress on GrantFox.

👏 Great work, @devwums! Keep contributing to tosirano.