[BUG] Remote trigger MCP connections broken after v1→v2 migration

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Description

Remote triggers with MCP connections (Slack, Gmail, Notion, Google Calendar) have stopped working. The triggers were functioning correctly until recently.

## Steps to Reproduce

1. Have an existing remote trigger with mcp_connections configured (created under v1 format)
2. Trigger runs on schedule but produces no output (no MCP tool calls succeed)
3. Attempting to create a new trigger with mcp_connections in the body returns:

HTTP 400
"translate job_config v1→v2: job_config is not a valid CreateSessionRequest:
proto: (line 1:485): unknown field "mcp_connections""

1. Updating the existing trigger's mcp_connections via the update API succeeds (HTTP 200), but manually running the trigger still produces no output
2. Even a minimal test prompt ("send a Slack DM to user X") fails to execute any MCP tool

## Expected Behavior

• Remote triggers should be able to use MCP connections as they did before
• Creating new triggers with mcp_connections should work
• mcp_connections field should be properly handled in the v1→v2 job_config translation

## Actual Behavior

• mcp_connections is rejected as an unknown field during v1→v2 translation on create
• Existing triggers with MCP connections silently fail — no MCP tools are called, no output is produced
• The same MCP tools work perfectly in local CLI sessions, confirming the issue is specific to remote trigger execution

## Environment

• Claude Code CLI (latest)
• Platform: Windows 11
• MCP connectors: claude.ai Slack, Gmail, Notion, Google Calendar (all connected and valid)
• Environment: anthropic_cloud (claude-code-default)

What Should Happen?

-

Error Messages/Logs

Steps to Reproduce

-

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.90

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Cursor

Additional Information

_No response_