refactor(channels): make built-in channels self-contained (#4908)

* refactor(channels): own setup and instance contracts

* refactor(channels): isolate management contracts

* refactor(channels): normalize activation contracts

* fix(channels): enforce management contracts

* refactor(channels): finish setup ownership migration

* fix(channels): harden management contracts

* fix(channels): enforce lazy loading and runtime ownership

* fix(feishu): make multi-instance startup idempotent

* fix(webui): render channel setup contracts cleanly

* fix(feishu): stop websocket clients cleanly

* fix(channels): enforce persistence and activation gates

* fix(channels): preserve global feature action scope

* fix(channels): apply defaults for single plugins

* fix(channels): enforce management contract boundaries

* refactor(feishu): remove identity helper indirection

* fix(channels): preserve management setup contracts

* refactor(channels): generalize instance settings UI

* refactor(channels): package channel plugins with web UI metadata

* refactor(channels): make built-ins self-contained packages

* test(channels): colocate tests with channel packages

* fix(dingtalk): use official brand icon

* feat(channels): colocate webui translations

* docs(channels): clarify plugin ownership

* test(exec): remove output wait race

* refactor(channels): unify plugin descriptors

* fix(channels): enforce descriptor-owned contracts

* refactor(channels): finish package-owned plugin setup

* refactor(channels): use repository-owned packages only

* fix(channels): self-describe dependencies and runtime state

* fix(channels): warn about legacy entry points

webui/src/i18n/locales/ja/common.json

@@ -513,13 +513,51 @@
       "needsConfig": "設定が必要",
       "connect": "接続",
       "reconnect": "再接続",
-      "feishuQrAlt": "Feishu 接続 QR コード",
-      "feishuScanTitle": "Feishu でスキャン",
-      "feishuScanDescription": "スマートフォンの Feishu または Lark でこのコードをスキャンしてください。認可後、nanobot が自動で設定を完了します。",
-      "feishuWaiting": "認可を待っています...",
-      "feishuConnected": "Feishu に接続しました。",
-      "feishuConnectStopped": "接続を停止しました。",
-      "feishuConnecting": "接続中..."
+      "advanced": "詳細設定",
+      "checkAndEnable": "確認して有効化",
+      "checkConnection": "接続を確認",
+      "checkedAndEnabled": "確認して有効化しました。",
+      "checking": "確認中...",
+      "checkOnly": "確認のみ",
+      "commandCopied": "コマンドをコピーしました。",
+      "commandCopyFailed": "コマンドをコピーできませんでした。",
+      "configuredInstances": "{{count}} 個のインスタンスを設定済み",
+      "connectPreview": "次の手順でブラウザー内接続を行います。今は下のコマンドを実行してください。",
+      "copyCommand": "コマンドをコピー",
+      "filterAll": "すべて",
+      "filterOff": "オフ",
+      "filterOn": "オン",
+      "helperCopied": "{{name}} をコピーしました。",
+      "helperCopyFailed": "{{name}} をコピーできませんでした。",
+      "hideSecret": "シークレットを隠す",
+      "instanceConfigured": "設定済み",
+      "instanceNeedsSetup": "設定が必要",
+      "runtimeFailed": "起動失敗",
+      "runtimeStarting": "起動中",
+      "runtimeStopped": "未実行",
+      "managedByWebui": "WebUI で管理",
+      "officialGuide": "公式ガイド",
+      "optional": "任意",
+      "providerPreset": "プロバイダー",
+      "requiredSetup": "必要な設定",
+      "savedSecret": "保存済み",
+      "savedSecretPlaceholder": "保存済みのシークレット",
+      "savedSettings": "設定を保存しました。",
+      "saveSettings": "設定を保存",
+      "selectChannel": "{{name}} の設定を表示",
+      "setupSteps": "次の手順",
+      "showSecret": "シークレットを表示",
+      "toggleChannel": "{{name}} チャンネル",
+      "toggleInstance": "{{name}} インスタンス",
+      "tryIt": "試してみる",
+      "validationFailed": "有効化する前に必要な設定を確認してください。",
+      "validation": {
+        "connected": "接続済み",
+        "configured": "手動設定済み",
+        "needs_setup": "設定が必要",
+        "invalid": "無効",
+        "unsupported": "手動設定"
+      }
     },
     "nanobotFeatures": {
       "enabled": "有効",