feat: 渠道管理分两块(.env必要回退+删除同步+可用类型/已保存分开)

agent-120 .env只留必要回退:
- .env.example KOOK移4可选业务字段(RECEIVE_MODE/WEBHOOK_PATH/VERIFY_TOKEN/ENCRYPT_KEY),只留token/base_url; channelAccountsFromEnv不读这4个; 说明业务字段走channelConfigForm.channels.json
- 黑名单/限流/receive_mode等走管理面板热更新, env仅必要连接回退

agent-121 删除渠道列表同步(根因: adminListChannels枚举caps,删除不同步caps):
- adminListChannels 以channels.json为准: 遍历caps时已删账号adapter跳过(s.channels注入时), 删除/保存后列表=channels.json, 删除即消失
- (capReg Remove后续可加,范围外标注)

agent-122 渠道管理分两块显示(主人:不割裂):
- ①可用适配器类型(顶部PLATFORM_TYPES全集grid卡片,已配置/未配置Tag,点新建配置)
- ②已保存配置(下方AdminTable过滤accounts>0,账号+bot身份+掩码token提示+连接/断开/删除)
- 拆 channelConfigForm.tsx(248行) 表单抽出; Channels.tsx 463→306行; token只回填hint不写值(保存留空不改secret)
全仓 build/vet/test绿+前端build绿(356KB)

frontend/web/src/admin/modules/channelFields.ts

@@ -68,3 +68,16 @@ export const PLATFORM_GUIDE: Record<string, PlatformGuide> = {
     tokenRequired: false,
   },
 };
+
+/** Human-friendly platform display name (the map key is the adapter prefix). */
+export const PLATFORM_LABEL: Record<string, string> = {
+  kook: "KOOK",
+  "qq-obv11": "QQ（OneBot v11）",
+  telegram: "Telegram",
+  "weixin-ilink": "微信（iLink）",
+  webhook: "Webhook",
+};
+
+/** The full set of known adapter platform types (whether or not configured yet).
+ *  Drives the "可用适配器类型（新建）" grid — every known type is creatable. */
+export const PLATFORM_TYPES: string[] = Object.keys(PLATFORM_GUIDE);