feat: add storage quota limit for S3/R2 channels

- Add quota counter tracking (usedMB, fileCount) per channel
- Filter channels by quota threshold in fetchUploadConfig()
- Update quota on upload (endUpload) and delete
- Add /api/manage/quota API for stats and recalculation
- Fix null check in delete when file record not found
- Fix R2 channel name from hardcoded to actual channel.name

functions/utils/sysConfig.js

@@ -4,6 +4,45 @@ import { getPageConfig } from '../api/manage/sysConfig/page';
 import { getOthersConfig } from '../api/manage/sysConfig/others';
 import { getDatabase } from './databaseAdapter.js';
 
+/**
+ * 根据容量限制过滤渠道
+ * @param {Object} db - 数据库实例
+ * @param {Array} channels - 渠道列表
+ * @returns {Array} 过滤后的渠道列表
+ */
+async function filterChannelsByQuota(db, channels) {
+    const result = [];
+    for (const channel of channels) {
+        // 未启用容量限制，直接通过
+        if (!channel.quota?.enabled || !channel.quota?.limitGB) {
+            result.push(channel);
+            continue;
+        }
+
+        try {
+            const quotaKey = `manage@quota@${channel.name}`;
+            const quotaData = await db.get(quotaKey);
+            const quota = quotaData ? JSON.parse(quotaData) : { usedMB: 0, fileCount: 0 };
+
+            const usedGB = quota.usedMB / 1024;
+            const limitGB = channel.quota.limitGB;
+            const threshold = channel.quota.threshold || 95;
+
+            // 未超过阈值，渠道可用
+            if ((usedGB / limitGB) * 100 < threshold) {
+                result.push(channel);
+            } else {
+                console.log(`Channel ${channel.name} quota exceeded: ${usedGB.toFixed(2)}GB / ${limitGB}GB (${threshold}% threshold)`);
+            }
+        } catch (error) {
+            console.error(`Failed to check quota for channel ${channel.name}:`, error);
+            // 检查失败时保守处理，允许使用该渠道
+            result.push(channel);
+        }
+    }
+    return result;
+}
+
 export async function fetchUploadConfig(env) {
     try {
         const db = getDatabase(env);
@@ -13,6 +52,10 @@ export async function fetchUploadConfig(env) {
         settings.cfr2.channels = settings.cfr2.channels.filter((channel) => channel.enabled);
         settings.s3.channels = settings.s3.channels.filter((channel) => channel.enabled);
 
+        // 根据容量限制过滤渠道（仅 R2 和 S3）
+        settings.cfr2.channels = await filterChannelsByQuota(db, settings.cfr2.channels);
+        settings.s3.channels = await filterChannelsByQuota(db, settings.s3.channels);
+
         return settings;
     } catch (error) {
         console.error('Failed to fetch upload config:', error);