spec: bitwise operations (bitwise-and/or/xor/not, arithmetic-shift, bit-count, integer-length)

OCaml: land/lor/lxor/lnot/lsl/asr in sx_primitives.ml
JS: & | ^ ~ << >> with Kernighan popcount and Math.clz32 for integer-length
spec/primitives.sx: stdlib.bitwise module with 7 entries
26 tests, 158 assertions, all pass OCaml+JS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

spec/primitives.sx

@@ -805,3 +805,47 @@
   :doc "Create a new empty mutable string buffer for O(1) amortised append.")
 
 (define-module :stdlib.coroutines)
+
+(define-module :stdlib.bitwise)
+
+(define-primitive
+  "bitwise-and"
+  :params (((a :as number) (b :as number)))
+  :returns "number"
+  :doc "Bitwise AND of two integers.")
+
+(define-primitive
+  "bitwise-or"
+  :params (((a :as number) (b :as number)))
+  :returns "number"
+  :doc "Bitwise OR of two integers.")
+
+(define-primitive
+  "bitwise-xor"
+  :params (((a :as number) (b :as number)))
+  :returns "number"
+  :doc "Bitwise XOR of two integers.")
+
+(define-primitive
+  "bitwise-not"
+  :params ((a :as number))
+  :returns "number"
+  :doc "Bitwise NOT (one's complement) of an integer.")
+
+(define-primitive
+  "arithmetic-shift"
+  :params (((a :as number) (count :as number)))
+  :returns "number"
+  :doc "Arithmetic shift: left if count > 0, right if count < 0.")
+
+(define-primitive
+  "bit-count"
+  :params ((a :as number))
+  :returns "number"
+  :doc "Count set bits (popcount) in a non-negative integer.")
+
+(define-primitive
+  "integer-length"
+  :params ((a :as number))
+  :returns "number"
+  :doc "Number of bits needed to represent integer a (excluding sign).")