Replace HTTPie subprocess calls with native libsoup3 async API. This
eliminates external dependencies and uses GNOME-standard async patterns.
Changes:
- Rewrite http_client.py to use libsoup3 Session and Message APIs
- Replace threading with GLib async callbacks in window.py
- Remove HTTPie dependency from Flatpak manifest
- Update documentation to reflect libsoup3 usage
Benefits:
- No external dependencies (HTTPie removed)
- Native GLib async integration (no threading complexity)
- Better performance with connection pooling and HTTP/2 support
- Cleaner codebase following GNOME development patterns
Pavel Baksy
28e904b191