- vacuum_station._parse_iso_utc was a verbatim copy of
water_purifier._parse_iso_utc; promoted to common.parse_iso_utc and
pointed both families at it. Also made it tzinfo-aware rather than
unconditionally overwriting with UTC -- harmless today since every
dump seen is a bare or Z-suffixed UTC timestamp, but a board that
ever emits a real offset would otherwise have it silently clobbered.
- Added the new vacuum_station type to the README's supported-appliance
table, and noted that combi microwaves route through the oven
registry.