feat: implement UserRegistry contract with profile management functions

src/UserRegistry.cairo

@@ -0,0 +1,76 @@
+#[starknet::contract]
+mod UserRegistry {
+    use starknet::contract_address::ContractAddress;
+    use starknet::storage;
+    use starknet::syscalls::get_caller_address;
+    use core::integer::u128;
+
+    #[derive(Drop, Copy, Serde)]
+    struct Profile {
+        id: u128,
+        user_address: ContractAddress,
+        name: felt252,
+        is_active: bool,
+    }
+
+    #[storage]
+    struct Storage {
+        profiles: Map<u128, Profile>,
+        profile_by_address: Map<ContractAddress, u128>, // Maps address to profile ID
+        profile_count: u128, // Tracks the total number of profiles
+    }
+
+    #[event]
+    struct ProfileUpdated {
+        user: ContractAddress,
+    }
+
+    #[event]
+    struct ProfileDeactivated {
+        user: ContractAddress,
+    }
+
+    #[starknet::interface]
+    trait IUserRegistry<TContractState> {
+        fn update_profile(ref self: TContractState, name: felt252);
+        fn deactivate_profile(ref self: TContractState);
+        fn get_profile_by_id(self: @TContractState, id: u128) -> Profile;
+        fn get_profile_by_address(self: @TContractState, address: ContractAddress) -> Profile;
+    }
+
+    #[external(v0)]
+    impl IUserRegistry<ContractState> of IUserRegistry<ContractState> {
+        fn update_profile(ref self: ContractState, name: felt252) {
+            let caller = get_caller_address();
+            let id = self.profile_by_address.get(caller).unwrap_or_else(|| panic!("Profile not found"));
+
+            let mut profile = self.profiles.get(id).unwrap_or_else(|| panic!("Profile not found"));
+            assert!(profile.user_address == caller, "Unauthorized");
+
+            profile.name = name;
+            self.profiles.insert(id, profile);
+            self.emit(ProfileUpdated { user: caller });
+        }
+
+        fn deactivate_profile(ref self: ContractState) {
+            let caller = get_caller_address();
+            let id = self.profile_by_address.get(caller).unwrap_or_else(|| panic!("Profile not found"));
+
+            let mut profile = self.profiles.get(id).unwrap_or_else(|| panic!("Profile not found"));
+            assert!(profile.user_address == caller, "Unauthorized");
+
+            profile.is_active = false;
+            self.profiles.insert(id, profile);
+            self.emit(ProfileDeactivated { user: caller });
+        }
+
+        fn get_profile_by_id(self: @ContractState, id: u128) -> Profile {
+            return self.profiles.get(id).unwrap_or_else(|| panic!("Profile not found"));
+        }
+
+        fn get_profile_by_address(self: @ContractState, address: ContractAddress) -> Profile {
+            let id = self.profile_by_address.get(address).unwrap_or_else(|| panic!("Profile not found"));
+            return self.profiles.get(id).unwrap_or_else(|| panic!("Profile not found"));
+        }
+    }
+}

src/interfaces/IUserRegistry.cairo

@@ -1 +1,16 @@
 
+#[starknet::interface]
+trait IUserRegistry<TContractState> {
+    /// Updates the name of the caller's profile
+    fn update_profile(ref self: TContractState, name: felt252);
+
+    /// Deactivates the caller's profile without data loss
+    fn deactivate_profile(ref self: TContractState);
+
+    /// Retrieves a profile by its unique ID
+    fn get_profile_by_id(self: @TContractState, id: u128) -> Profile;
+
+    /// Retrieves a profile by the associated wallet address
+    fn get_profile_by_address(self: @TContractState, address: ContractAddress) -> Profile;
+}
+