Phase 2: Move core spec files to spec/ and spec/tests/

git mv eval.sx, parser.sx, primitives.sx, render.sx, cek.sx, frames.sx,
continuations.sx, callcc.sx, types.sx, special-forms.sx → spec/
Tests → spec/tests/
Both bootstrappers verified — find files via spec/ → web/ → shared/sx/ref/

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

spec/boundary-core.sx

@@ -1,49 +0,0 @@
-;; ==========================================================================
-;; boundary.sx — SX language boundary contract
-;;
-;; Declares the core I/O primitives that any SX host must provide.
-;; This is the LANGUAGE contract — not deployment-specific.
-;;
-;; Pure primitives (Tier 1) are declared in primitives.sx.
-;; Deployment-specific I/O lives in boundary-app.sx.
-;; Per-service page helpers live in {service}/sx/boundary.sx.
-;;
-;; Format:
-;;   (define-io-primitive "name"
-;;     :params (param1 param2 &key ...)
-;;     :returns "type"
-;;     :effects [io]
-;;     :async true
-;;     :doc "description"
-;;     :context :request)
-;;
-;; ==========================================================================
-
-
-;; --------------------------------------------------------------------------
-;; Tier 1: Pure primitives — declared in primitives.sx
-;; --------------------------------------------------------------------------
-
-(declare-tier :pure :source "primitives.sx")
-
-
-;; --------------------------------------------------------------------------
-;; Core platform primitives — type inspection + environment
-;; --------------------------------------------------------------------------
-;;
-;; These are provided by every host. Not IO, not web-specific.
-
-(declare-core-primitive "type-of"
-  :params (value)
-  :returns "string"
-  :doc "Return the type name of a value.")
-
-(declare-core-primitive "make-env"
-  :params ()
-  :returns "dict"
-  :doc "Create a base environment with all primitives.")
-
-(declare-core-primitive "identical?"
-  :params (a b)
-  :returns "boolean"
-  :doc "Reference equality check.")