Round 6 of the seed shrink (the printer round, scoped by the perf wall). The
five wrappers move to 20-coll over two new host seams: __write (push a string
to *out*) and __pr-str1 (render one value readably). The renderer itself
stays in the seed — it's representation-coupled (pvec/phm/phs/sorted
internals) and shared with the hot str, and rendering through overlay calls
would pay the per-element call cost everywhere big values get printed.
print-method as a real multimethod is follow-up work.
The new spec rows caught a renderer bug: string bodies were never escaped, so
(pr-str "a\"b") didn't round-trip through the reader. pr-render now
escapes quote/backslash/control chars per Clojure.
1de5ede246