* fix(acp-bridge): preserve original timestamp when replaying session history
History replay re-emits each persisted record with its original epoch-ms time nested in update._meta, but BridgeClient.sessionUpdate published the frame without lifting it to the envelope. EventBus.publish then stamped envelope _meta.serverTimestamp with publish-time Date.now(), which the client's extractServerTimestamp picks up at higher priority than the nested original — so a resumed session rendered every historical message at the resume moment instead of when it was sent.
Lift update._meta.timestamp (or serverTimestamp) to the envelope serverTimestamp so EventBus preserves it. Live updates without such a timestamp keep the Date.now() fallback unchanged.
* feat(web-shell): show each history message's time on hover
Carry each transcript block's wall-clock time (serverTimestamp ?? clientReceivedAt) onto every message and reveal it as a CSS-only hover tooltip in the message list. Same-day messages show HH:mm:ss; older ones show yyyy-MM-dd HH:mm:ss (local time, zero-padded).
