Step 5 piece 6: migrate 23 .sx files to define-library/import

Wraps all core .sx files in R7RS define-library with explicit export
lists, plus (import ...) at end for backward-compatible global re-export.

Libraries registered:
  (sx bytecode)      — 83 opcode constants
  (sx render)        — 15 tag registries + render helpers
  (sx signals)       — 23 reactive signal primitives
  (sx r7rs)          — 21 R7RS aliases
  (sx compiler)      — 42 compiler functions
  (sx vm)            — 32 VM functions
  (sx freeze)        — 9 freeze/thaw functions
  (sx content)       — 6 content store functions
  (sx callcc)        — 1 call/cc wrapper
  (sx highlight)     — 13 syntax highlighting functions
  (sx stdlib)        — 47 stdlib functions
  (sx swap)          — 13 swap algebra functions
  (sx render-trace)  — 8 render trace functions
  (sx harness)       — 21 test harness functions
  (sx canonical)     — 12 canonical serialization functions
  (web adapter-html) — 13 HTML renderer functions
  (web adapter-sx)   — 13 SX wire format functions
  (web engine)       — 33 hypermedia engine functions
  (web request-handler) — 4 request handling functions
  (web page-helpers) — 12 page helper functions
  (web router)       — 36 routing functions
  (web deps)         — 19 dependency analysis functions
  (web orchestration) — 59 page orchestration functions

Key changes:
- define-library now inherits parent env (env-extend env instead of
  env-extend make-env) so library bodies can access platform primitives
- sx_server.ml: added resolve_library_path + load_library_file for
  import resolution (maps library specs to file paths)
- cek_run_with_io: handles "import" locally instead of sending to
  Python bridge

2608/2608 tests passing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/bytecode.sx

@@ -19,6 +19,94 @@
 ;; --------------------------------------------------------------------------
 
 ;; Stack / Constants
+
+(define-library (sx bytecode)
+  (export
+    OP_CONST
+    OP_NIL
+    OP_TRUE
+    OP_FALSE
+    OP_POP
+    OP_DUP
+    OP_LOCAL_GET
+    OP_LOCAL_SET
+    OP_UPVALUE_GET
+    OP_UPVALUE_SET
+    OP_GLOBAL_GET
+    OP_GLOBAL_SET
+    OP_JUMP
+    OP_JUMP_IF_FALSE
+    OP_JUMP_IF_TRUE
+    OP_CALL
+    OP_TAIL_CALL
+    OP_RETURN
+    OP_CLOSURE
+    OP_CALL_PRIM
+    OP_APPLY
+    OP_LIST
+    OP_DICT
+    OP_APPEND_BANG
+    OP_ITER_INIT
+    OP_ITER_NEXT
+    OP_MAP_OPEN
+    OP_MAP_APPEND
+    OP_MAP_CLOSE
+    OP_FILTER_TEST
+    OP_HO_MAP
+    OP_HO_FILTER
+    OP_HO_REDUCE
+    OP_HO_FOR_EACH
+    OP_HO_SOME
+    OP_HO_EVERY
+    OP_SCOPE_PUSH
+    OP_SCOPE_POP
+    OP_PROVIDE_PUSH
+    OP_PROVIDE_POP
+    OP_CONTEXT
+    OP_EMIT
+    OP_EMITTED
+    OP_RESET
+    OP_SHIFT
+    OP_DEFINE
+    OP_DEFCOMP
+    OP_DEFISLAND
+    OP_DEFMACRO
+    OP_EXPAND_MACRO
+    OP_STR_CONCAT
+    OP_STR_JOIN
+    OP_SERIALIZE
+    OP_ADD
+    OP_SUB
+    OP_MUL
+    OP_DIV
+    OP_EQ
+    OP_LT
+    OP_GT
+    OP_NOT
+    OP_LEN
+    OP_FIRST
+    OP_REST
+    OP_NTH
+    OP_CONS
+    OP_NEG
+    OP_INC
+    OP_DEC
+    OP_ASER_TAG
+    OP_ASER_FRAG
+    BYTECODE_MAGIC
+    BYTECODE_VERSION
+    CONST_NUMBER
+    CONST_STRING
+    CONST_BOOL
+    CONST_NIL
+    CONST_SYMBOL
+    CONST_KEYWORD
+    CONST_LIST
+    CONST_DICT
+    CONST_CODE
+    opcode-name)
+  (begin
+
 (define OP_CONST          1)  ;; u16 pool_idx — push constant
 (define OP_NIL            2)  ;; push nil
 (define OP_TRUE           3)  ;; push true
@@ -161,3 +249,9 @@
       (= op 50) "RETURN"   (= op 52) "CALL_PRIM"
       (= op 128) "DEFINE"   (= op 144) "STR_CONCAT"
       :else (str "OP_" op))))
+
+
+)) ;; end define-library
+
+;; Re-export to global namespace for backward compatibility
+(import (sx bytecode))