read-all reads every top-level form of a string (the parse-all the compile path
needs in inc 6). With this the portable reader covers everything reader.janet does
(atoms 5a, collections+quote/meta 5b, dispatch 5c, multi-form 5d).
Validated: reader-parity 149/149 (every construct); jolt.reader compiles and runs
on build/jolt ((require [jolt.reader]) (read-all …) works natively). The
interpreted reader overflows the eval stack on large/deeply-nested files, so real-
file/full-corpus validation happens when it's cross-compiled and run on Chez
(inc 7). Position tracking (checker) and the actual wire-in replacing reader.ss are
deferred — they ride inc 6 (jolt.reader on Chez). See new beads.