Inlines `check_network_path` from crate::network::commands into
commands_v2/legacy_compat.rs. The legacy command was a one-line wrapper
over crate::network::is_network_path; the inlined v2 form calls
is_network_path directly with no behavior change.
Deletes the legacy #[tauri::command] definition in network/mod.rs.
Other tauri commands inside crate::network::commands remain (they have
no v2 delegates and keep being exported as their own legacy commands;
they will be addressed in a separate cleanup step if needed).
No frontend invoke changes required.
Step 6 of the legacy cleanup plan, group G (network path).
cc
vicrodh
81461bec32