Refactor: Overly complex manual HTTP/Socket handling in WorkshopClient

The WorkshopClient class implements low-level HTTP communication, including manual header parsing (e.g., in src/workshopclient.cpp:16-29) and complex asynchronous socket management (src/workshopclient.cpp:145-572). \n\nThis manual implementation is prone to errors and violates the principle of leveraging higher-level KDE Frameworks components. The entire networking layer (socket connection, read/write loop, header parsing, timeout logic) should ideally be refactored to use or a dedicated KF6 networking module, allowing Qt to handle the complexities of HTTP protocol adherence, retries, and asynchronous state management more robustly. This would significantly reduce boilerplate code and improve reliability.\n\nLocation: src/workshopclient.cpp

Start by reviewing src/workshopclient.cpp:16-29 for manual header parsing and src/workshopclient.cpp:145-572 for socket, read/write, timeout, and asynchronous state handling. Determine which higher-level KDE Frameworks or KF6 networking component fits, then consider the work complete when the networking layer no longer manages these concerns manually and preserves the client's behavior.

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