(refactor): unify globals into CONSTANTS/APP_STATE and polish info pill
Replace scattered vars (configData, state, saveTimerId, menuCommandId,
CONFIG_KEY, magic strings) with two structured objects: CONSTANTS for
immutable config (selectors, keys, enums, URLs) and APP_STATE for
mutable runtime state. Also swap glassmorphism on the info pill for a
solid dark background, fixed height, and tabular-nums font feature.