Adds `client` event reporting appid/title/tagmask once per managed
client per output during state-update batches. Closes the gap where
consumers could see per-tag client counts but not per-tag client
identities.
Bumps zdwl_ipc_output_v2 interface to v3 and zdwl_ipc_manager_v2
global advertisement to v3. Implementation localized to
dwl_ipc_output_printstatus_to in src/ext-protocol/dwl-ipc.h.