Remove CSSX style dictionary infrastructure — styling is just components

The entire parallel CSS system (StyleValue type, style dictionary,
keyword atom resolver, content-addressed class generation, runtime
CSS injection, localStorage caching) was built but never adopted —
the codebase already uses :class strings with defcomp components
for all styling. Remove ~3,000 lines of unused infrastructure.

Deleted:
- cssx.sx spec module (317 lines)
- style_dict.py (782 lines) and style_resolver.py (254 lines)
- StyleValue type, defkeyframes special form, build-keyframes platform fn
- Style dict JSON delivery (<script type="text/sx-styles">), cookies, localStorage
- css/merge-styles primitives, inject-style-value, fnv1a-hash platform interface

Simplified:
- defstyle now binds any value (string, function) — no StyleValue type needed
- render-attrs no longer special-cases :style StyleValue → class conversion
- Boot sequence skips style dict init step

Preserved:
- tw.css parsing + CSS class delivery (SX-Css headers, <style id="sx-css">)
- All component infrastructure (defcomp, caching, bundling, deps)
- defstyle as a binding form for reusable class strings

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

shared/sx/ref/adapter-dom.sx

@@ -52,9 +52,6 @@
           (create-fragment)
           (render-dom-list expr env ns))
 
-      ;; Style value → text of class name
-      "style-value" (create-text-node (style-value-class expr))
-
       ;; Fallback
       :else (create-text-node (str expr)))))
 
@@ -147,8 +144,7 @@
     (let ((new-ns (cond (= tag "svg") SVG_NS
                         (= tag "math") MATH_NS
                         :else ns))
-          (el (dom-create-element tag new-ns))
-          (extra-class nil))
+          (el (dom-create-element tag new-ns)))
 
       ;; Process args: keywords → attrs, others → children
       (reduce
@@ -168,9 +164,6 @@
                     ;; nil or false → skip
                     (or (nil? attr-val) (= attr-val false))
                       nil
-                    ;; :style StyleValue → convert to class
-                    (and (= attr-name "style") (style-value? attr-val))
-                      (set! extra-class (style-value-class attr-val))
                     ;; Boolean attr
                     (contains? BOOLEAN_ATTRS attr-name)
                       (when attr-val (dom-set-attr el attr-name ""))
@@ -190,12 +183,6 @@
         (dict "i" 0 "skip" false)
         args)
 
-      ;; Merge StyleValue class
-      (when extra-class
-        (let ((existing (dom-get-attr el "class")))
-          (dom-set-attr el "class"
-            (if existing (str existing " " extra-class) extra-class))))
-
       el)))
 
 
@@ -297,7 +284,7 @@
 
 (define RENDER_DOM_FORMS
   (list "if" "when" "cond" "case" "let" "let*" "begin" "do"
-        "define" "defcomp" "defmacro" "defstyle" "defkeyframes" "defhandler"
+        "define" "defcomp" "defmacro" "defstyle" "defhandler"
         "map" "map-indexed" "filter" "for-each"))
 
 (define render-dom-form?
@@ -450,7 +437,6 @@
 ;;
 ;; From render.sx:
 ;;   HTML_TAGS, VOID_ELEMENTS, BOOLEAN_ATTRS, definition-form?
-;;   style-value?, style-value-class
 ;;
 ;; From eval.sx:
 ;;   eval-expr, trampoline, expand-macro, process-bindings, eval-cond