c11c510b42
When the agent is busy and the user sends multiple text follow-ups, the interrupt-mode and steer-fallback path stored them via merge_pending_message_event(merge_text=True), which newline-joins consecutive TEXT messages into a SINGLE pending turn — collapsing two separate user messages into one mashed-together turn and destroying the message boundaries the user sees (#43066 sub-bug 2). Route that storage through _queue_or_replace_pending_event (the same FIFO infrastructure used by busy queue-mode and /queue) so each follow-up gets its own next-turn slot in arrival order, while still preserving photo-burst / album merge semantics for media. Pure queue-mode already used FIFO; this brings the interrupt/steer-fallback path in line. The sibling defect in #43066 (assistant messages lost after compaction) was already fixed on main by the identity-tracking flush rewrite (#46053) plus the pre-rotation flush (#47202), so this only addresses the remaining busy-message-merge half. Co-authored-by: KiruyaMomochi <65301509+KiruyaMomochi@users.noreply.github.com>