fix: early name validation, fighter glow, reduced visual noise

- Add /api/auth/check-name endpoint for early name availability check
- JoinBoutPage checks name availability at naming step (not after webhook)
- FightCardPage: replace poster containers with circular glow behind sprites
- Reduce synthwave grid and CRT overlay opacity for cleaner backgrounds
- BotProfilePage: webhook management, owner-only fields
- useNostr: normalize bot data, guard auto-restore, clearAllState helper
- bots.ts: expose owner-only webhook info on stats endpoint

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/JoinBoutPage.vue

@@ -144,6 +144,7 @@ function handleGenerateLogin() {
 }
 
 async function handleNsecBackupDone() {
+  if (isLoading) return
   showNsecBackup.value = false
   try {
     const result = await login()
@@ -206,7 +207,9 @@ function pickCharacter(id: string) {
   step.value = 'name-bot'
 }
 
-function confirmName() {
+const isCheckingName = ref(false)
+
+async function confirmName() {
   const name = botName.value.trim()
   if (!name || name.length < 2) {
     error.value = 'Name must be at least 2 characters.'
@@ -217,6 +220,21 @@ function confirmName() {
     return
   }
   error.value = ''
+  isCheckingName.value = true
+  try {
+    const res = await fetch(`/api/auth/check-name/${encodeURIComponent(name)}`)
+    if (res.ok) {
+      const data = await res.json()
+      if (!data.available) {
+        error.value = 'That name is taken. Pick another.'
+        return
+      }
+    }
+  } catch {
+    // If check fails, proceed anyway — server will catch it at registration
+  } finally {
+    isCheckingName.value = false
+  }
   step.value = 'bot-setup'
 }
 
@@ -269,6 +287,21 @@ async function confirmHumanName() {
     return
   }
   error.value = ''
+  isCheckingName.value = true
+  try {
+    const res = await fetch(`/api/auth/check-name/${encodeURIComponent(name)}`)
+    if (res.ok) {
+      const data = await res.json()
+      if (!data.available) {
+        error.value = 'That name is taken. Pick another.'
+        return
+      }
+    }
+  } catch {
+    // proceed — server catches at registration
+  } finally {
+    isCheckingName.value = false
+  }
   step.value = 'human-guide'
 }
 
@@ -598,10 +631,14 @@ function handleSignOut() {
           <button
             class="flex-1 py-3 bg-neon-cyan/10 border-2 border-neon-cyan/50 text-neon-cyan
                    font-display font-bold text-sm tracking-wider
-                   hover:bg-neon-cyan/20 transition-all"
+                   hover:bg-neon-cyan/20 transition-all
+                   disabled:opacity-50 disabled:cursor-wait
+                   flex items-center justify-center gap-2"
+            :disabled="isCheckingName"
             @click="confirmName"
           >
-            NEXT
+            <span v-if="isCheckingName" class="w-4 h-4 border-2 border-neon-cyan/30 border-t-neon-cyan rounded-full animate-spin" />
+            {{ isCheckingName ? 'CHECKING...' : 'NEXT' }}
           </button>
         </div>
       </template>
@@ -852,10 +889,14 @@ function handleSignOut() {
           <button
             class="flex-1 py-3 bg-neon-pink/10 border-2 border-neon-pink/50 text-neon-pink
                    font-display font-bold text-sm tracking-wider
-                   hover:bg-neon-pink/20 transition-all"
+                   hover:bg-neon-pink/20 transition-all
+                   disabled:opacity-50 disabled:cursor-wait
+                   flex items-center justify-center gap-2"
+            :disabled="isCheckingName"
             @click="confirmHumanName"
           >
-            NEXT
+            <span v-if="isCheckingName" class="w-4 h-4 border-2 border-neon-pink/30 border-t-neon-pink rounded-full animate-spin" />
+            {{ isCheckingName ? 'CHECKING...' : 'NEXT' }}
           </button>
         </div>
       </template>