[zuudevs]

Summary

Reorganizes the internal src/ tree so high-level/public API implementations no longer sit loose at the source root.

New layout

src/
├── core/
│   ├── client.cpp
│   ├── headers.cpp
│   └── url.cpp
├── http/
├── net/
├── platform/
└── CMakeLists.txt

Changes

• move src/client.cpp -> src/core/client.cpp
• move src/headers.cpp -> src/core/headers.cpp
• move src/url.cpp -> src/core/url.cpp
• keep existing http/, net/, and platform/ architectural boundaries unchanged
• remove obsolete src/dummy.cpp
• update src/CMakeLists.txt source paths

Behavior

No runtime/API behavior changes are intended. GitHub detects all three implementation moves as exact renames with zero content changes.

Rationale

The project is growing past the initial foundation stage. Keeping public/core implementation files at the src/ root makes future client state, redirect, and connection-reuse work harder to navigate. A dedicated core/ layer makes the physical source layout match the architectural separation already documented in the repository.

Follow-up

A separate PR will tighten GitHub Actions path filters so documentation-only changes do not run the full C++ build/test matrix.