Fix Compilation Errors: Add Missing Imports and Fix String Conversions

[1nonlypiece]

Summary

This PR fixes multiple compilation errors in the Predictify Hybrid contract by adding missing imports and correcting string conversion methods.

Changes Made

1. Fixed Missing vec! Macro Import

File: contracts/predictify-hybrid/src/resolution.rs

• Added vec to the main soroban_sdk imports
• Removed duplicate import in test module

2. Added Missing Type Imports

File: contracts/predictify-hybrid/src/voting.rs

• Added use crate::types::{OracleConfig, OracleProvider}; to test module
• Fixes undeclared type errors for OracleConfig and OracleProvider

3. Fixed String Conversion Methods

File: contracts/predictify-hybrid/src/utils.rs

• Replaced all s.unpack() calls with s.to_string()
• Replaced all s.as_str() calls with s.to_string()
• Updated string manipulation functions to use proper soroban_sdk::String methods
• Fixed methods: to_uppercase, to_lowercase, trim, truncate, split, join, contains, starts_with, ends_with, replace, validate_string_length, sanitize_string, string_to_i128, validate_email, validate_url

4. Added Missing Trait Import

File: contracts/predictify-hybrid/src/test.rs

• Added use crate::oracles::OracleInterface; import
• Fixes missing get_price method for ReflectorOracle

Technical Details

String Conversion Fix

The main issue was incorrect usage of string conversion methods:

• Before: s.unpack() and s.as_str() (not available on soroban_sdk::String)
• After: s.to_string() (correct method for soroban_sdk::String)

Import Strategy

• Added imports at the appropriate scope level
• Used qualified imports to avoid naming conflicts
• Maintained existing import structure

Testing

• ✅ All compilation errors resolved
• ✅ Contract builds successfully
• ✅ Tests can now run (runtime errors are separate issue)

Files Changed

• contracts/predictify-hybrid/src/resolution.rs
• contracts/predictify-hybrid/src/voting.rs
• contracts/predictify-hybrid/src/utils.rs
• contracts/predictify-hybrid/src/test.rs

Breaking Changes

None - this is purely a compilation fix.

Related Issues

Closes #120

Checklist

• Code compiles successfully
• No new warnings introduced
• Existing functionality preserved
• Proper error handling maintained
• Documentation updated where necessary