What

45 throw std:: statements remain in 11 files across the network_system. The facade layer is the worst offender:

• tcp_facade.cpp — 12 throws
• quic_facade.cpp — 8 throws
• udp_facade.cpp — 5 throws
• websocket_facade.cpp — 3 throws
• http_facade.cpp — 2 throws

The ecosystem convention is Result<T> (from common_system), and the core/internal layers already use it. This creates a mixed error-handling contract.

Why

Callers cannot use a uniform error-handling pattern. Functions that throw require try/catch while adjacent functions return Result<T>.

How

Technical Approach

1. Change facade return types from raw shared_ptr to common::Result<shared_ptr<...>>
2. Replace throw std::invalid_argument(...) with return Result::err(...)
3. Update corresponding .h headers with new signatures
4. Update test assertions

Acceptance Criteria

• All 5 facade files return Result<T> instead of throwing
• All 45 throw sites converted
• Corresponding headers updated
• Existing tests pass with Result-based assertions