fix: read clash mode tolerantly and propagate mode-switch failures

The home mode card read the proxy mode only from mihomo's /configs (strict
BaseConfig); when that response drifted a single field, the whole read
failed and the card showed a bare "communication error". patch_clash_mode
also swallowed backend PATCH failures and always returned Ok, so the UI
could not tell a switch had actually failed.

- add a tolerant get_clash_mode command that reads mode from the saved
  clash config (IClashTemp::get_mode), bypassing strict BaseConfig
  deserialization, and
- make change_clash_mode return Result and have patch_clash_mode propagate
  it; the hotkey/tray callers log-and-ignore as before.

src-tauri/src/lib.rs

@@ -160,6 +160,7 @@ mod app_init {
             cmd::get_clash_info,
             cmd::patch_clash_config,
             cmd::patch_clash_mode,
+            cmd::get_clash_mode,
             cmd::change_clash_core,
             cmd::get_runtime_config,
             cmd::get_runtime_yaml,