fix: API Key permissions multi-select save and display issue

- Fix updateApiKey to use JSON.stringify for permissions field
- Add comma-separated string handling in normalizePermissions
- Add frontend parsing for comma-separated permissions format

Fixes issue where selecting multiple permissions (e.g. Claude + OpenAI)
would be saved as "claude,openai" instead of '["claude","openai"]'

web/admin-spa/src/components/apikeys/EditApiKeyModal.vue

@@ -1246,6 +1246,12 @@ onMounted(async () => {
       } catch {
         perms = VALID_PERMS.includes(perms) ? [perms] : []
       }
+    } else if (perms.includes(',')) {
+      // 兼容逗号分隔格式（如 "claude,openai"）
+      perms = perms
+        .split(',')
+        .map((p) => p.trim())
+        .filter((p) => VALID_PERMS.includes(p))
     } else if (VALID_PERMS.includes(perms)) {
       perms = [perms]
     } else {