Add bigdec min/max (review follow-up)

Review found (< 1M 2M) worked but (min 1M 2M) threw — incoherent. Wire min/max
the same way as the other ops: value-position jolt-min/jolt-max shims (new in
seq.ss, added to core-value-procs) and call-position via bd-spec/bd-ops ->
jbd-min/jbd-max.

min/max return the original operand by value, not a coerced copy, matching
Clojure: (min 1M 2.0) -> 1M, (max 1M 2.0) -> 2.0, (min 1.50M 2M) -> 1.50M; a tie
keeps the second operand ((max 1.5M 1.50M) -> 1.50M). bigdec mixed with a flonum
in call position stays in the documented :any/contagion gap (value position
handles it). Re-mint; 6 more JVM-certified rows.

host/chez/seq.ss

@@ -134,6 +134,8 @@
 (define (jolt-sub . xs) (apply - xs))
 (define (jolt-mul . xs) (apply * xs))
 (define (jolt-div . xs) (apply / xs))
+(define (jolt-min . xs) (apply min xs))
+(define (jolt-max . xs) (apply max xs))
 
 ;; ============================================================================
 ;; IFn dispatch — the dynamic "value as fn" fallback. A callee that the emitter