feat: replace panel proxy URL with outbound-based egress bridge

Instead of requiring a manual SOCKS5/HTTP URL, the panel now lets the
admin pick an Xray outbound from a dropdown (same UX as Geodata
Auto-Update). At runtime, injectPanelEgress appends a loopback SOCKS
inbound (tag: panel-egress) and prepends a routing rule so the panel's
own HTTP traffic — version checks, Telegram, normal geo-file updates —
is routed through the chosen outbound. Xray-native Geodata Auto-Update
is unaffected (it uses its own geodata.outbound inside Xray). Blackhole
outbounds are excluded from both picker dropdowns since routing any
download through one just drops it. Translations updated for all 13
locales.

frontend/src/generated/examples.ts

@@ -26,7 +26,7 @@ export const EXAMPLES: Record<string, unknown> = {
     "ldapUserFilter": "",
     "ldapVlessField": "",
     "pageSize": 0,
-    "panelProxy": "",
+    "panelOutbound": "",
     "remarkModel": "",
     "restartXrayOnClientDisable": false,
     "sessionMaxAge": 1,
@@ -115,7 +115,7 @@ export const EXAMPLES: Record<string, unknown> = {
     "ldapUserFilter": "",
     "ldapVlessField": "",
     "pageSize": 0,
-    "panelProxy": "",
+    "panelOutbound": "",
     "remarkModel": "",
     "restartXrayOnClientDisable": false,
     "sessionMaxAge": 1,