Add Specs section, Reflexive Web essay, fix highlight and dev caching

- Fix highlight() returning SxExpr so syntax-highlighted code renders
  as DOM elements instead of leaking SX source text into the page
- Add Specs section that reads and displays canonical SX spec files
  from shared/sx/ref/ with syntax highlighting
- Add "The Reflexive Web" essay on SX becoming a complete LISP with
  AI as native participant
- Change logo from (<x>) to (<sx>) everywhere
- Unify all backgrounds to bg-stone-100, center code blocks
- Skip component/style cookie cache in dev mode so .sx edits are
  visible immediately on refresh without clearing localStorage

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

sx/sxc/pages/docs.sx

@@ -240,4 +240,42 @@
     "tail-call-optimization" (~essay-tail-call-optimization)
     "continuations" (~essay-continuations)
     "godel-escher-bach" (~essay-godel-escher-bach)
+    "reflexive-web" (~essay-reflexive-web)
     :else (~essay-sx-sucks)))
+
+;; ---------------------------------------------------------------------------
+;; Specs section
+;; ---------------------------------------------------------------------------
+
+(defpage specs-index
+  :path "/specs/"
+  :auth :public
+  :layout (:sx-section
+    :section "Specs"
+    :sub-label "Specs"
+    :sub-href "/specs/core"
+    :sub-nav (~section-nav :items specs-nav-items :current "Core")
+    :selected "Core")
+  :data (spec-data "core")
+  :content (~spec-core-content :spec-files spec-files))
+
+(defpage specs-page
+  :path "/specs/<slug>"
+  :auth :public
+  :layout (:sx-section
+    :section "Specs"
+    :sub-label "Specs"
+    :sub-href "/specs/core"
+    :sub-nav (~section-nav :items specs-nav-items
+               :current (find-current specs-nav-items slug))
+    :selected (or (find-current specs-nav-items slug) ""))
+  :data (spec-data slug)
+  :content (if spec-not-found
+    (~spec-not-found :slug slug)
+    (case slug
+      "core" (~spec-core-content :spec-files spec-files)
+      :else (~spec-detail-content
+        :spec-title spec-title
+        :spec-desc spec-desc
+        :spec-filename spec-filename
+        :spec-source spec-source))))

sx/sxc/pages/helpers.py

@@ -16,6 +16,7 @@ def _register_sx_helpers() -> None:
         "primitives-data": _primitives_data,
         "reference-data": _reference_data,
         "attr-detail-data": _attr_detail_data,
+        "spec-data": _spec_data,
     })
 
 
@@ -103,6 +104,63 @@ def _reference_data(slug: str) -> dict:
     }
 
 
+_SPEC_FILES = {
+    "parser": ("parser.sx", "Parser", "Tokenization and parsing of SX source text into AST."),
+    "evaluator": ("eval.sx", "Evaluator", "Tree-walking evaluation of SX expressions."),
+    "primitives": ("primitives.sx", "Primitives", "All built-in pure functions and their signatures."),
+    "renderer": ("render.sx", "Renderer", "Rendering evaluated expressions to DOM, HTML, or SX wire format."),
+}
+
+
+def _spec_data(slug: str) -> dict:
+    """Return spec file source and highlighted version for display."""
+    import os
+    from content.highlight import highlight as _highlight
+
+    ref_dir = os.path.join(os.path.dirname(__file__), "..", "..", "shared", "sx", "ref")
+    # Normalise — inside container shared is at /app/shared
+    if not os.path.isdir(ref_dir):
+        ref_dir = "/app/shared/sx/ref"
+
+    base = {"spec-not-found": None, "spec-title": None, "spec-desc": None,
+            "spec-filename": None, "spec-source": None, "spec-files": None}
+
+    if slug == "core":
+        specs = []
+        for key in ("parser", "evaluator", "primitives", "renderer"):
+            filename, title, desc = _SPEC_FILES[key]
+            filepath = os.path.join(ref_dir, filename)
+            source = _read_spec(filepath)
+            specs.append({
+                "title": title,
+                "desc": desc,
+                "filename": filename,
+                "source": source,
+                "href": f"/specs/{key}",
+            })
+        return {**base, "spec-title": "SX Core Specification", "spec-files": specs}
+
+    info = _SPEC_FILES.get(slug)
+    if not info:
+        return {**base, "spec-not-found": True}
+
+    filename, title, desc = info
+    filepath = os.path.join(ref_dir, filename)
+    source = _read_spec(filepath)
+    return {**base,
+            "spec-title": title, "spec-desc": desc,
+            "spec-filename": filename, "spec-source": source}
+
+
+def _read_spec(filepath: str) -> str:
+    """Read a spec file, returning empty string if missing."""
+    try:
+        with open(filepath, encoding="utf-8") as f:
+            return f.read()
+    except FileNotFoundError:
+        return ";; spec file not found"
+
+
 def _attr_detail_data(slug: str) -> dict:
     """Return attribute detail data for a specific attribute slug.