- scripts/messaging.py: add logged_at param to create_message; use provided value or fall back to _now_utc()
- dev-api.py: add logged_at: Optional[str] = None to MessageCreateBody
- web/src/stores/messaging.ts: remove logged_at from Omit, add as optional intersection so callers can pass it through
- web/src/components/MessageLogModal.vue: pass logged_at in handleSubmit payload; move @keydown.esc from backdrop to modal-dialog (which holds focus); compute localNow fresh inside watch so it reflects actual open time
