feat(security): harden gateway boundaries and usage policies

Consolidate subscription usage policy enforcement, privacy-safe persistence, and gateway security hardening into one reviewable change.

Includes bounded HTTP and execution envelopes, header and protocol guards, DNS and relay validation, authentication and secret projection hardening, secure backup/install paths, and regression coverage.

frontend/src/features/pool/components/PoolAccountBatchDialog.vue

@@ -322,6 +322,7 @@ import ProxyNodeSelect from '@/features/providers/components/ProxyNodeSelect.vue
 import { useToast } from '@/composables/useToast'
 import { useConfirm } from '@/composables/useConfirm'
 import { parseApiError } from '@/utils/errorParser'
+import { log } from '@/utils/logger'
 import {
   batchActionPoolKeys,
   getPoolBatchDeleteTask,
@@ -669,8 +670,7 @@ async function executeAction(actionOverride?: PoolBatchActionValue): Promise<voi
             successCount += 1
           } catch (err) {
             failedCount += 1
-            // eslint-disable-next-line no-console
-            console.error(`[PoolAccountBatchDialog] export failed (${key.key_id}):`, err)
+            log.error('Pool account credential export failed', err)
           } finally {
             progressDone.value += 1
           }
@@ -716,8 +716,7 @@ async function executeAction(actionOverride?: PoolBatchActionValue): Promise<voi
             successCount += result.affected
           }
         } catch (err) {
-          // eslint-disable-next-line no-console
-          console.error(`batch delete failed (batch ${batchIndex}/${totalBatches}):`, err)
+          log.error('Pool account batch delete failed', err)
           failedCount += batch.length
         }
 
@@ -749,8 +748,7 @@ async function executeAction(actionOverride?: PoolBatchActionValue): Promise<voi
           })
           successCount += result.affected
         } catch (err) {
-          // eslint-disable-next-line no-console
-          console.error(`batch ${selectedAction.value} failed (batch ${batchIndex}/${totalBatches}):`, err)
+          log.error('Pool account batch action failed', err)
           failedCount += batch.length
         }
 
@@ -797,8 +795,7 @@ async function executeAction(actionOverride?: PoolBatchActionValue): Promise<voi
   } catch (err) {
     showError(parseApiError(err, '批量操作失败'))
   } finally {
-    // eslint-disable-next-line no-console
-    console.info('[PoolAccountBatchDialog] executeAction timing', {
+    log.info('Pool account batch action timing', {
       providerId: props.providerId,
       action: selectedAction.value,
       requestedCount,