fix: key the cache on all response-shaping settings

wttrin--make-cache-key keyed only on location and unit system, but the request
body also depends on wttrin-display-options and wttrin-default-languages.
Changing display options or language mid-session served the old cached response,
and the staleness header then claimed it was current for the new settings. The
key now includes every setting that shapes the response.

Cache-key tests rewritten to assert behavior (distinct key per varying setting,
stable key for identical settings) instead of an exact key string.

0 files changed, 0 insertions, 0 deletions