Session C groundwork: Werkator's git-metadata mask needs a tmpfs
BETWEEN binds (ro-bind .git, tmpfs .git/werkator, bind workspace), so
-v and --tmpfs now collect into one ordered mount list and RunSpec
carries Mounts instead of Binds. --tmpfs DEST is the docker flag of the
same name. `werkdock images` lists loaded image names one per line, so
a consumer can check existence through the CLI. -v accepts the explicit
:rw docker default instead of refusing it.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
