v1.16: architecture split, networking reorg, and coverage hardening

[maxches99]

Summary

• split NetworkClient internals into orchestrator + HTTP execution pipeline + offline replay coordinator boundaries
• split WebSocket internals around connection/ack/outbound queue management flows
• reorganized Sources/NovaNetworkClient/Networking into focused subfolders: Client, Core, Cache, OfflineQueue, Policies
• preserved public API while reducing internal coupling and improving testability
• removed repository docs that were moved to Confluence; kept release note docs/WHATS_NEW_v1.16.md

Validation

• swift build
• swift test --enable-code-coverage
• RUN_E2E_TESTS=1 swift test --filter E2ECoverageTests
• swift run NovaNetworkClientBenchmarks --check-baseline (passed)

DoD Notes

• public API unchanged
• no latency regression vs baseline benchmark check
• coverage maintained above target by lines/functions