Strict reader tokens; edn mode with the reference's error contracts

The reader now rejects what the JVM reader rejects: a token that starts
like a number but doesn't parse is NumberFormatException (1a, 08, 0x2g,
2r2 — never a symbol); ratio parts are digit runs (1/-1 invalid) with a
zero denominator throwing ArithmeticException; empty ns/name parts are
invalid tokens (:, ::, foo/, /foo) while /, ns//, and :/ stay valid;
duplicate map keys and set elements throw at read; unsupported string
escapes and octal escapes past \377 throw; a stray close delimiter is
'Unmatched delimiter'; \r ends line comments. #inst validates its
calendar fields progressively (leap years included) and #uuid demands
canonical hex. 1-arg symbol splits its ns at the FIRST slash
(Symbol.intern): (symbol "foo/bar/baz") is foo/"bar/baz".

clojure.edn gets its own strict seam (__read-form-edn): auto-resolved
keywords are invalid there, every #_ discarded form validates through the
same :readers/:default pipeline (an unreadable tagged element throws even
when discarded), built-in tags win over :default, M literals construct
BigDecimals, lists satisfy list?, and EOF honors :eof — an opts map
without :eof makes end-of-input an error.

clojure.edn-test.read-string goes 246 pass / 46 fail / 5 errors -> 297/0/0
(fully clean). cts baseline 5904 -> 5955 pass, 23 errors, 56 baselined
namespaces. 9 JVM-certified corpus rows; reader spec section.

test/chez/cts-known-failures.txt

@@ -57,4 +57,3 @@ clojure.core-test.update 1 0
 clojure.core-test.vals 0 3
 clojure.core-test.vec 1 0
 clojure.core-test.when-let 1 0
-clojure.edn-test.read-string 46 5