fix(clients): bump auto-generated email length to 10 chars

The "create" form opened with a 9-char random email default, the bulk
modal's random portion was only 6 chars, and the inbound-defaults seed
used 8 — all below the 10-char minimum we want for new clients. Bring
each generator to 10 so an unedited auto-generated email meets the
threshold without the user having to extend it.

frontend/src/lib/xray/inbound-defaults.ts

@@ -46,7 +46,7 @@ interface ClientBase {
 
 function clientBase(seed: ClientBaseSeed = {}): ClientBase {
   return {
-    email: seed.email ?? RandomUtil.randomLowerAndNum(8),
+    email: seed.email ?? RandomUtil.randomLowerAndNum(10),
     limitIp: seed.limitIp ?? 0,
     totalGB: seed.totalGB ?? 0,
     expiryTime: seed.expiryTime ?? 0,