CsAC Client v0.3.0

CsAC Client v0.3.0

• Adapted the desktop client to the UniCsAC unified API endpoint.
• Removed legacy API fallback routes and old .php client route usage.
• Refreshed the desktop UI with a cleaner blue-white visual style.
• Improved chat layout, conversation flow, and interaction smoothness.
• Updated account, group, friend, report, avatar, and message calls for the new backend.