feat(Clash): Add routing rules and enable routing option for Clash subscriptions (#4904)

* feat(clash): add routing rules and enable routing option for Clash/Mihomo subscriptions

Allows adding custom YAML blocks and placeholders to Clash exports.

Why: Shifting routing to the client prevents server IP exposure for
DIRECT traffic and reduces unnecessary server bandwidth/CPU usage.

* fix

---------

Co-authored-by: Misfit-s <>

frontend/src/models/setting.ts

@@ -55,6 +55,8 @@ export class AllSetting {
   subURI = '';
   subJsonURI = '';
   subClashURI = '';
+  subClashEnableRouting = false;
+  subClashRules = '';
   subJsonFragment = '';
   subJsonNoises = '';
   subJsonMux = '';