refactor: rename generic DataKey and MilestoneStatus enums to contract-specific names and update error types.

Author: 0xdevcollins

contracts/bounty_registry/src/contract.rs

@@ -3,7 +3,7 @@ use soroban_sdk::contracterror;
 #[contracterror]
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 #[repr(u32)]
-pub enum Error {
+pub enum BountyError {
     AlreadyInitialized = 700,
     NotInitialized = 701,
     NotAuthorized = 702,

contracts/bounty_registry/src/error.rs

@@ -58,7 +58,7 @@ pub struct Application {
 }
 
 #[contracttype]
-pub enum DataKey {
+pub enum BountyDataKey {
     Admin,
     CoreEscrow,
     ReputationRegistry,