fix(collab): use '-' instead of ':' in agent page-history jobId

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.

apps/server/src/collaboration/extensions/persistence.extension.ts

@@ -324,7 +324,10 @@ export class PersistenceExtension implements Extension {
       : pageAge < HISTORY_FAST_THRESHOLD
         ? HISTORY_FAST_INTERVAL
         : HISTORY_INTERVAL;
-    const jobId = isAgent ? `${page.id}:agent` : page.id;
+    // BullMQ forbids ':' in custom job IDs (it is the Redis key separator), so
+    // use '-' here. page.id is a UUID, so `${page.id}-agent` cannot collide with
+    // any human job whose id is a bare page.id.
+    const jobId = isAgent ? `${page.id}-agent` : page.id;
 
     await this.historyQueue.add(
       QueueJob.PAGE_HISTORY,