Phase 14 fixes: pr-str mapping, every-pred, PLAN.md update
- compiler.janet: fix core-pr-str mapping — was pointing to core-str (line 221)
- core.janet: add core-pr-str (string/format-based serialization with proper quoting),
add core-every-pred (variadic predicate composition), wire both into core-bindings
- cljs-port-5.janet: restore var-dynamic? test, with-meta preserves test,
add pr-str keyword and every-pred assertions
- PLAN.md: update to current state — all phases 0-14 checked off, 316/317
316 ok, 1 fail (pre-existing, unchanged)
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