chatinfo,updates: sync archived dialogs as low priority

[davidjirovec]

Summary

• map Telegram's archive folder (folder_id = 1) to Matrix m.lowpriority during dialog sync
• handle updateFolderPeers so archive and unarchive changes update the room tag
• preserve m.favourite precedence when an archived dialog is pinned
• clear stale bridge-managed tags for dialogs that are neither pinned nor archived

This restores archive-tag behavior that existed in the legacy Python bridge and was discussed in #832. The Go connector currently only emits m.favourite for pinned dialogs and ignores updateFolderPeers.

Live archive changes continue to respect the bridge-wide tag_only_on_create setting. Deployments that set it to true will only apply the tag when a portal room is created.

Testing

• go test ./pkg/connector
• go vet ./pkg/connector
• go test ./... (all completed packages passed; the executable package could not compile locally because the system olm/olm.h header is not installed)