Fix blank Xray Settings page from wrapped xrayTemplateConfig (#4059) (#4069)

`getXraySetting` builds its response as

    { "xraySetting": <db value>, "inboundTags": ..., "outboundTestUrl": ... }

and embeds the raw DB value as the `xraySetting` field without
checking whether the stored value already has that exact shape.

The frontend pulls the textarea content from `result.xraySetting`
and saves it back verbatim. If the DB ever ends up holding the
response-shaped wrapper instead of a real xray config (older
installs where this happened at least once, users who imported a
copy-pasted response into the textarea, a botched migration, etc.),
the next save nests another layer, the one after that nests a
third, and the Vue-side JSON.parse of the resulting blob silently
fails — the Xray Settings page goes blank.

Fix both ends of the round-trip:

* Add `service.UnwrapXrayTemplateConfig`. It peels off any number of
  `xraySetting`-keyed layers, leaving a real xray config behind.
  The check is conservative: if the outer object already contains
  any top-level xray key (`inbounds`, `outbounds`, `routing`, `api`,
  `dns`, `log`, `policy`, `stats`), it is returned unchanged, and
  there is a depth cap to avoid pathological inputs.

* `SaveXraySetting` unwraps before validation so a round-tripped
  wrapper from an already-corrupted page can no longer re-poison
  the DB on save.

* `getXraySetting` unwraps on read and, when it finds a wrapper,
  rewrites the DB with the corrected value. Existing broken installs
  heal themselves on the next visit to the page.

Includes unit tests for the passthrough, single-wrap, multi-wrap,
string-encoded-inner, and false-positive cases.

Co-authored-by: pwnnex <eternxles@gmail.com>

web/controller/xray_setting.go

@@ -49,6 +49,23 @@ func (a *XraySettingController) getXraySetting(c *gin.Context) {
 		jsonMsg(c, I18nWeb(c, "pages.settings.toasts.getSettings"), err)
 		return
 	}
+	// Older versions of this handler embedded the raw DB value as
+	// `xraySetting` in the response without checking if the value
+	// already had that wrapper shape. When the frontend saved it
+	// back through the textarea verbatim, the wrapper got persisted
+	// and every subsequent save nested another layer, which is what
+	// eventually produced the blank Xray Settings page in #4059.
+	// Strip any such wrapper here, and heal the DB if we found one so
+	// the next read is O(1) instead of climbing the same pile again.
+	if unwrapped := service.UnwrapXrayTemplateConfig(xraySetting); unwrapped != xraySetting {
+		if saveErr := a.XraySettingService.SaveXraySetting(unwrapped); saveErr == nil {
+			xraySetting = unwrapped
+		} else {
+			// Don't fail the read — just serve the unwrapped value
+			// and leave the DB healing for a later save.
+			xraySetting = unwrapped
+		}
+	}
 	inboundTags, err := a.InboundService.GetInboundTags()
 	if err != nil {
 		jsonMsg(c, I18nWeb(c, "pages.settings.toasts.getSettings"), err)