Stalwart 1.0 checks names more strictly than its capability says: a
reserved name may not be the stem either (`con.txt`, `Aux.tar.gz`), and
control characters are refused (macOS `Icon\r`). Names over 255 bytes
of UTF-8 were never accepted. Uploaded names are now made acceptable
before they are sent: control characters become "_", a reserved stem
gets "_" after it (`con.txt` becomes `con_.txt`), and a long name is
shortened, keeping its extension. The rename and new-folder dialogs
refuse such names with their own messages. The rules apply wherever the
server publishes naming rules, so 0.16.6 to 0.16.23 get `con_.txt` too.
One refused file used to abort a whole upload. Uploads now go on and
report the files that failed at the end, and a folder upload skips the
contents of a folder it could not create instead of dropping them into
the folder the upload started in. What would sit deeper than 1.0's
`maxFileNodeDepth` (64) is left out before it is uploaded, and a folder
copy that would go past it fails before the first create.
File errors keep their JMAP type, and the Files toasts now say why an
action failed: too many files or folders (`overQuota`), folders nested
too deeply, a refused name, missing rights, or a file too large. New
and copied files get a bare lowercase media type, which 1.0 requires.
