feat(adapters): mark EBA-superseded adapters as legacy and collapse them

The 12 old adapters that now have an EBA replacement are tagged
`spec.legacy: true` in their source manifests. Principle: don't delete,
de-emphasize.

- sources/*.yaml (aiocqhttp, dingtalk, discord, kook, lark,
  officialaccount, qqofficial, slack, telegram, wecom, wecombot,
  wecomcs): add spec.legacy: true
- Adapter / IChooseAdapterEntity types: add optional legacy flag
- BotForm adapter Select: split legacy adapters into a collapsed,
  grayscale group at the bottom with an explanatory hint; auto-expand
  when the bot already uses a legacy adapter
- Wizard platform picker: same collapsed legacy section
- i18n: legacyAdapters / legacyAdaptersHint (zh-Hans, en-US)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/langbot/pkg/platform/sources/aiocqhttp.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: OneBot v11 適配器，用於接入 QQ 機器人協定端，請查看文件了解使用方式
   icon: onebot.png
 spec:
+  legacy: true
   categories:
     - protocol
   help_links:

src/langbot/pkg/platform/sources/dingtalk.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: 釘釘適配器，請查看文件了解使用方式
   icon: dingtalk.svg
 spec:
+  legacy: true
   categories:
     - china
   help_links:

src/langbot/pkg/platform/sources/discord.yaml

@@ -20,6 +20,7 @@ metadata:
     es_ES: Adaptador de Discord, requiere un entorno de red con acceso al servidor de Discord
   icon: discord.svg
 spec:
+  legacy: true
   categories:
     - popular
     - global

src/langbot/pkg/platform/sources/kook.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: KOOK 適配器（原開黑啦），支援頻道訊息和私聊訊息
   icon: kook.png
 spec:
+  legacy: true
   categories:
     - china
   help_links:

src/langbot/pkg/platform/sources/lark.yaml

@@ -14,6 +14,7 @@ metadata:
     ja_JP: Lark アダプター、長期接続およびWebhookモードの両方をサポートしています。使用方法の詳細については、ドキュメントを参照してください。
   icon: lark.svg
 spec:
+  legacy: true
   categories:
     - popular
     - china

src/langbot/pkg/platform/sources/officialaccount.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: 微信公眾號適配器，需要公網地址以接收訊息推送，請查看文件了解使用方式
   icon: officialaccount.png
 spec:
+  legacy: true
   categories:
     - china
   help_links:

src/langbot/pkg/platform/sources/qqofficial.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: QQ 官方 API，支援 Webhook 和 WebSocket 兩種連線模式
   icon: qqofficial.svg
 spec:
+  legacy: true
   categories:
     - china
   help_links:

src/langbot/pkg/platform/sources/slack.yaml

@@ -20,6 +20,7 @@ metadata:
     es_ES: Adaptador de Slack, requiere una dirección pública para recibir notificaciones de mensajes de Slack, consulte la documentación para obtener instrucciones de uso
   icon: slack.png
 spec:
+  legacy: true
   categories:
     - popular
     - global

src/langbot/pkg/platform/sources/telegram.yaml

@@ -20,6 +20,7 @@ metadata:
     es_ES: Adaptador de Telegram, consulte la documentación para obtener instrucciones de uso
   icon: telegram.svg
 spec:
+  legacy: true
   categories:
     - popular
     - global

src/langbot/pkg/platform/sources/wecom.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: 企業微信內部機器人，請查看文件了解使用方式
   icon: wecom.png
 spec:
+  legacy: true
   categories:
     - popular
     - china

src/langbot/pkg/platform/sources/wecombot.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: 企業微信智慧機器人，支援長連線和 Webhook 兩種接入方式，請查看文件了解使用方式
   icon: wecombot.png
 spec:
+  legacy: true
   categories:
     - china
   help_links:

src/langbot/pkg/platform/sources/wecomcs.yaml

@@ -12,6 +12,7 @@ metadata:
     zh_Hant: 企業微信對外客服機器人，需要公網地址以接收訊息推送，請查看文件了解使用方式
   icon: wecom.png
 spec:
+  legacy: true
   categories:
     - china
   help_links: