fix: prevent page crash when deleting an agent (#514)

src/i18n/locales/en/agents.json

@@ -41,6 +41,7 @@
         "agentCreated": "Agent created",
         "agentCreateFailed": "Failed to create agent: {{error}}",
         "agentDeleted": "Agent deleted",
+        "agentDeleteFailed": "Failed to delete agent: {{error}}",
         "agentUpdated": "Agent updated",
         "agentUpdateFailed": "Failed to update agent: {{error}}",
         "channelAssigned": "{{channel}} assigned to agent",

src/i18n/locales/ja/agents.json

@@ -41,6 +41,7 @@
         "agentCreated": "Agent を作成しました",
         "agentCreateFailed": "Agent の作成に失敗しました: {{error}}",
         "agentDeleted": "Agent を削除しました",
+        "agentDeleteFailed": "Agent の削除に失敗しました: {{error}}",
         "agentUpdated": "Agent を更新しました",
         "agentUpdateFailed": "Agent の更新に失敗しました: {{error}}",
         "channelAssigned": "{{channel}} を Agent に割り当てました",

src/i18n/locales/zh/agents.json

@@ -41,6 +41,7 @@
         "agentCreated": "Agent 已创建",
         "agentCreateFailed": "创建 Agent 失败：{{error}}",
         "agentDeleted": "Agent 已删除",
+        "agentDeleteFailed": "删除 Agent 失败：{{error}}",
         "agentUpdated": "Agent 已更新",
         "agentUpdateFailed": "更新 Agent 失败：{{error}}",
         "channelAssigned": "{{channel}} 已分配给 Agent",