BullMQ rejects custom job IDs containing ':' (Redis key separator),
throwing "Custom Id cannot contain :" inside the onStoreDocument hook
for every agent edit. This broke agent-driven page saves (MCP
create_page runs as actor='agent') with HTTP 400.
Switch the agent dedup suffix from `${page.id}:agent` to
`${page.id}-agent`. The jobId is only used as a BullMQ dedup key and is
never parsed by the history processor; page.id is a UUID, so the
hyphenated id cannot collide with a human job whose id is a bare page.id.