Merge eval.sx + frames.sx + cek.sx into single evaluator.sx

The core spec is now one file: spec/evaluator.sx (2275 lines).
Three parts:
  Part 1: CEK frames — state and continuation frame constructors
  Part 2: Evaluation utilities — call, parse, define, macro, strict
  Part 3: CEK machine — the sole evaluator

Deleted:
- spec/eval.sx (merged into evaluator.sx)
- spec/frames.sx (merged into evaluator.sx)
- spec/cek.sx (merged into evaluator.sx)
- spec/continuations.sx (dead — CEK handles shift/reset natively)

Updated bootstrappers (JS + Python) to load evaluator.sx as core.
Removed frames/cek from SPEC_MODULES (now part of core).

Bundle size: 392KB → 377KB standard, 418KB → 403KB full.
All tests unchanged: JS 747/747, Full 864/870, Python 679/679.

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

hosts/javascript/platform.py

@@ -46,14 +46,12 @@ SPEC_MODULES = {
     "router": ("router.sx", "router (client-side route matching)"),
     "signals": ("signals.sx", "signals (reactive signal runtime)"),
     "page-helpers": ("page-helpers.sx", "page-helpers (pure data transformation helpers)"),
-    "frames": ("frames.sx", "frames (CEK continuation frames)"),
-    "cek": ("cek.sx", "cek (explicit CEK machine evaluator)"),
     "types": ("types.sx", "types (gradual type system)"),
 }
+# Note: frames and cek are now part of evaluator.sx (always loaded as core)
 
 # Explicit ordering for spec modules with dependencies.
-# Modules listed here are emitted in this order; any not listed use alphabetical.
-SPEC_MODULE_ORDER = ["deps", "frames", "page-helpers", "router", "cek", "signals", "types"]
+SPEC_MODULE_ORDER = ["deps", "page-helpers", "router", "signals", "types"]
 
 
 EXTENSION_NAMES = {"continuations"}