feat(strictness): assoc bounds, dissoc/count map-only, subvec bounds, numerator/denominator, min-key empty

- assoc on a vector bounds-checks the index (0..count); out-of-range/negative throw
- dissoc throws on non-maps (numbers/sequences/sets/scalars); nil ok; records/
  sorted-maps/meta-maps still handled
- count throws on scalars (numbers/keywords/symbols/booleans/chars)
- subvec validates vector type and 0<=start<=end<=count
- numerator/denominator always throw (Jolt has no ratio type)
- min-key/max-key throw on no values

count 18/2; dissoc 19/3; assoc 36/6; subvec 26/3/5; numerator/denominator throw
cases pass. clojure-test-suite pass 3840->3864. spec: map/strictness (16). jpm test green.

test/integration/clojure-test-suite-test.janet

@@ -18,7 +18,7 @@
 
 # Baseline: assertions Jolt currently passes across the suite. Raise as Jolt
 # improves so a regression (previously-passing assertion breaking) is caught.
-(def baseline-pass 3835)
+(def baseline-pass 3860)
 # A file is "clean" when it ran with zero failures AND zero errors.
 (def baseline-clean-files 45)
 # Per-file wall-clock budget (seconds). Normal files finish in well under 1s;

test/spec/maps-spec.janet

@@ -71,3 +71,23 @@
   ["key across repr"        ":v"              "(get (assoc {} (vec [1 2]) :v) [1 2])"]
   ["frequencies of maps"    "2"               "(get (frequencies [{:a 1} (hash-map :a 1)]) {:a 1})"]
   ["group-by collection key" "1"              "(count (group-by identity [{:a 1} (hash-map :a 1)]))"])
+
+# Strictness: assoc bounds-checks vector indices; dissoc requires a map;
+# count rejects scalars; numerator/denominator have no ratio type.
+(defspec "map / strictness (throws like Clojure)"
+  ["assoc vec out of bounds" :throws "(assoc [0 1 2] 4 4)"]
+  ["assoc vec negative"      :throws "(assoc [] -1 0)"]
+  ["assoc vec at count ok"   "[1 2 3]" "(assoc [1 2] 2 3)"]
+  ["dissoc on number"        :throws "(dissoc 42 :a)"]
+  ["dissoc on vector"        :throws "(dissoc [1 2] 0)"]
+  ["dissoc on set"           :throws "(dissoc #{:a} :a)"]
+  ["dissoc nil ok"           "nil"   "(dissoc nil :a)"]
+  ["count on number"         :throws "(count 1)"]
+  ["count on keyword"        :throws "(count :a)"]
+  ["count string ok"         "3"     "(count \"abc\")"]
+  ["numerator throws"        :throws "(numerator 1)"]
+  ["denominator throws"      :throws "(denominator 2)"]
+  ["subvec out of range"     :throws "(subvec [0 1 2 3] 1 5)"]
+  ["subvec start>end"        :throws "(subvec [0 1 2 3] 3 2)"]
+  ["subvec ok"               "[1 2]" "(subvec [0 1 2 3] 1 3)"]
+  ["min-key empty"           :throws "(apply min-key identity [])"])