Hashtags are auto-lowercased

Typing #ANY_UPPERCASE_LETTER_AFTER_A_HASHTAG it will auto-convert it to the lowercase version. Is this a bug or a feature?

Start by reproducing the hashtag behavior described in the issue, then trace the Keybase client chat input handling to find where uppercase letters are converted. Done would require an agreed decision on whether preserving uppercase is the intended behavior and a change or confirmation accordingly; the issue names no file or test.

Written by the indexing model from the issue text.