When searching from the sidebar while already on /search, the
SearchPage component stayed mounted and its internal state (allEvents,
isLoading) from the previous search would briefly flash before the
new query's effect could clear it.
Fix: wrap SearchPage with a keyed component that uses ?q as the React
key. When the query changes, React unmounts the old instance entirely
and mounts a fresh one — all state initializes cleanly from the new
URL with no transitional renders showing stale data.
Closes#72
Mary Kate Fain
15df41d59f