Browser sniffing helpers should be deprecated by default; expose the UA parser for general use

Browser sniffing helpers should be deprecated by default; expose the UA parser for general use: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). The Browser docs already say things like "use feature detection / progressive enhancement instead", and link to MDN's…