refactor: replace scope-level rate limiting with model-level rate limiting

Merge functional changes from develop branch:
- Remove AntigravityQuotaScope system (claude/gemini_text/gemini_image)
- Replace with per-model rate limiting using resolveAntigravityModelKey
- Remove model load statistics (IncrModelCallCount/GetModelLoadBatch)
- Simplify account selection to unified priority→load→LRU algorithm
- Remove SetAntigravityQuotaScopeLimit from AccountRepository
- Clean up scope-related UI indicators and API fields

frontend/src/views/admin/ops/components/OpsConcurrencyCard.vue

@@ -56,7 +56,6 @@ interface SummaryRow {
   total_accounts: number
   available_accounts: number
   rate_limited_accounts: number
-  scope_rate_limit_count?: Record<string, number>
   error_accounts: number
   // 并发统计
   total_concurrency: number
@@ -122,7 +121,7 @@ const platformRows = computed((): SummaryRow[] => {
       total_accounts: totalAccounts,
       available_accounts: availableAccounts,
       rate_limited_accounts: safeNumber(avail.rate_limit_count),
-      scope_rate_limit_count: avail.scope_rate_limit_count,
+
       error_accounts: safeNumber(avail.error_count),
       total_concurrency: totalConcurrency,
       used_concurrency: usedConcurrency,
@@ -162,7 +161,7 @@ const groupRows = computed((): SummaryRow[] => {
         total_accounts: totalAccounts,
         available_accounts: availableAccounts,
         rate_limited_accounts: safeNumber(avail.rate_limit_count),
-        scope_rate_limit_count: avail.scope_rate_limit_count,
+  
         error_accounts: safeNumber(avail.error_count),
         total_concurrency: totalConcurrency,
         used_concurrency: usedConcurrency,
@@ -329,14 +328,6 @@ function formatDuration(seconds: number): string {
   return `${hours}h`
 }
 
-function formatScopeName(scope: string): string {
-  const names: Record<string, string> = {
-    claude: 'Claude',
-    gemini_text: 'Gemini',
-    gemini_image: 'Image'
-  }
-  return names[scope] || scope
-}
 
 watch(
   () => realtimeEnabled.value,
@@ -505,18 +496,6 @@ watch(
               {{ t('admin.ops.concurrency.rateLimited', { count: row.rate_limited_accounts }) }}
             </span>
 
-            <!-- Scope 限流 (仅 Antigravity) -->
-            <template v-if="row.scope_rate_limit_count && Object.keys(row.scope_rate_limit_count).length > 0">
-              <span
-                v-for="(count, scope) in row.scope_rate_limit_count"
-                :key="scope"
-                class="rounded-full bg-orange-100 px-1.5 py-0.5 font-semibold text-orange-700 dark:bg-orange-900/30 dark:text-orange-400"
-                :title="t('admin.ops.concurrency.scopeRateLimitedTooltip', { scope, count })"
-              >
-                {{ formatScopeName(scope as string) }} {{ count }}
-              </span>
-            </template>
-
             <!-- 异常账号 -->
             <span
               v-if="row.error_accounts > 0"