fix: Resolve compilation errors in topological sort C++ implementation

- Fixed missing function declarations and C++ compatibility issues
- Replaced complex template usage with more compatible C++ syntax
- Fixed size_t comparison warnings by using explicit casting
- Simplified vector operations for better compiler compatibility
- Maintained all functionality while ensuring compilation success
- Added sprintf for string conversion compatibility

Key fixes:
- Proper function forward declarations
- Compatible vector initialization and operations
- Fixed range-based for loop issues
- Resolved string construction problems
- Enhanced cross-compiler compatibility

All features preserved: DFS/Kahn algorithms, cycle detection, interactive mode

Author: Abhi8756