Two breaking API changes in 0.2:
- `stash_assigns/2` is gone. Keys to persist are now declared on the
`use LiveStash, stored_keys: [...]` macro and `stash/1` picks them
up automatically.
- The TTL unit switched to seconds — this codebase never called the
TTL setter, so no config change is needed.
Updated both callers (MapLive persists selected_band + selected_time;
SubmitLive persists active_tab). `recover_state/1` signature is
unchanged. Full LiveView suite passes (67 tests).