refactor(vless): drop selectedAuth, expose two explicit auth buttons

selectedAuth was UI-only metadata (Xray never reads it) and entirely
redundant with the encryption string itself — the dropdown only
controlled which block from `xray vlessenc` to apply. Replace it with
two explicit buttons ("X25519" and "ML-KEM-768") so the user picks
the auth mode in one click instead of dropdown + Get-New-Keys.

- VLESSSettings drops the field from constructor, fromJson, and toJson;
  legacy `selectedAuth` values still in DB will be silently shed on the
  next save.
- getNewVlessEnc(authLabel) now takes the label as a parameter; clear
  resets only decryption/encryption.
- Fallbacks visibility now keys on encryption === "none" (the same
  thing the dropdown was effectively gating on).
- Info modal drops the redundant Authentication tag and colours the
  encryption tag red when it's "none", green otherwise.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/html/modals/inbound_modal.html

@@ -302,12 +302,11 @@
                 this.inbound.stream.tls.echServerKeys = "";
                 this.inbound.stream.tls.settings.echConfigList = "";
             },
-            async getNewVlessEnc() {
-                const selected = inModal.inbound.settings.selectedAuth;
-                if (!selected) {
-                    this.clearVlessEnc();
-                    return;
-                }
+            // Pulls the requested auth block from `xray vlessenc` (which always returns
+            // both X25519 and ML-KEM-768 variants) and applies it to the inbound's
+            // decryption/encryption strings. The auth mode is implied by the resulting
+            async getNewVlessEnc(authLabel) {
+                if (!authLabel) return;
 
                 inModal.loading(true);
                 const msg = await HttpUtil.get("/panel/api/server/getNewVlessEnc");
@@ -318,10 +317,10 @@
                 }
 
                 const auths = msg.obj.auths || [];
-                const block = auths.find((a) => a.label === selected);
+                const block = auths.find((a) => a.label === authLabel);
 
                 if (!block) {
-                    console.error("No auth block for", selected);
+                    console.error("No auth block for", authLabel);
                     return;
                 }
 
@@ -331,7 +330,6 @@
             clearVlessEnc() {
                 this.inbound.settings.decryption = "none";
                 this.inbound.settings.encryption = "none";
-                this.inbound.settings.selectedAuth = undefined;
             },
             // Vision Seed methods - must be in Vue methods for proper template binding.
             // Mirror the inModal helpers but use Vue.set so the form re-renders.