feat(sub): auto-detect subscription format by User-Agent (Updated) (#5826)

* feat(settings): add subscription format controls

* feat(sub): auto-detect subscription formats

* fix(xray): validate balancer regexes before save

* Revert "fix(xray): validate balancer regexes before save"

This reverts commit 8a208ce71b.

* doc(endpoints): align indent spaces

* doc(settings): improve error message formatting in validateSubUserAgentRegex

- Use NewErrorf with proper formatting instead of NewError with string concatenation
- Add comment explaining the rationale for returning original pattern value
- This preserves the intentional design where empty input is stored as empty
  in the DB and inherited as the runtime default at read time

---------

Co-authored-by: Tomilla <5007859+Tomilla@users.noreply.github.com>
Co-authored-by: Sanaei <ho3ein.sanaei@gmail.com>

frontend/src/models/setting.ts

@@ -29,6 +29,11 @@ export class AllSetting {
   xrayTemplateConfig = '';
   subEnable = true;
   subJsonEnable = false;
+  subJsonAutoDetect = false;
+  subJsonAlwaysArray = false;
+  subJsonUserAgentRegex = '';
+  subClashAutoDetect = false;
+  subClashUserAgentRegex = '';
   subTitle = '';
   subSupportUrl = '';
   subProfileUrl = '';