Issue: base64url sane decode and base64 sane decode accept invalid padding sequences

Issue: base64url sane decode and base64 sane decode accept invalid padding sequences: a task in LegoFlow-SWE (Harbor dataset). The base64url sane decode (and its base64 counterpart base64 sane decode ) are documented as “sane” decoders that ignore whitespace characters ( \t , \n , \r , ) and a…

The task

The `base64url_sane_decode` (and its base64 counterpart `base64_sane_decode`) are documented as “sane” decoders that ignore whitespace characters (`\t`, `\n`, `\r`, ` `) and a trailing NUL byte. However, they must still enforce proper padding rules: `=` padding characters are only valid when they appear **at most two…

Part of Lego-X/LegoFlow-SWE.