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/compiler.sx

@@ -14,6 +14,53 @@
 ;; --------------------------------------------------------------------------
 ;; Constant pool builder
 ;; --------------------------------------------------------------------------
+
+(define-library (sx compiler)
+  (export
+    make-pool
+    pool-add
+    make-scope
+    scope-define-local
+    scope-resolve
+    make-emitter
+    emit-byte
+    emit-u16
+    emit-i16
+    emit-op
+    emit-const
+    current-offset
+    patch-i16
+    compile-expr
+    compile-symbol
+    compile-dict
+    compile-list
+    compile-if
+    compile-when
+    compile-and
+    compile-or
+    compile-begin
+    compile-let
+    compile-letrec
+    compile-lambda
+    compile-define
+    compile-set
+    compile-quote
+    compile-cond
+    compile-case
+    compile-case-clauses
+    compile-match
+    compile-thread
+    compile-thread-step
+    compile-defcomp
+    compile-defmacro
+    compile-quasiquote
+    compile-qq-expr
+    compile-qq-list
+    compile-call
+    compile
+    compile-module)
+  (begin
+
 (define make-pool (fn () {:entries (if (primitive? "mutable-list") (mutable-list) (list)) :index {:_count 0}}))
 
 (define
@@ -871,3 +918,9 @@
       (compile-expr em (last exprs) scope false)
       (emit-op em 50)
       {:constants (get (get em "pool") "entries") :bytecode (get em "bytecode")})))
+
+
+)) ;; end define-library
+
+;; Re-export to global namespace for backward compatibility
+(import (sx compiler))