Feature request for Supabase Auth: Allow the usage of more than just digits (lowercase and/or uppercase letters) in the one-time passwords

Currently, Supabase Auth generates OTPs consisting only of 6 to 10 digits (function GenerateOtp in While numeric OTPs are standard, adding support for alphanumeric OTPs (lowercase and/or uppercase letters) would improve security and flexibility. Proposed feature: Introduce a configuration option allowing specifying the character set for OTPs, such as: • Numeric only (default, current behavior) • Alphanumeric (uppercase + lowercase + digits) • Alphanumeric with case control (lowercase only, uppercase only, or mixed) Use case: • Increased entropy for OTPs without increasing length. • Better compatibility with security policies that require non-numeric codes. • Customization based on application needs. Implementation: Add an optional setting in the Supabase Auth configuration config.Mailer.OtpCharset and forward it to an adjusted version of the GenerateOtp function. A not yet tested and probably too simple possible implemen…