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/html.py

@@ -27,7 +27,7 @@ from __future__ import annotations
 import contextvars
 from typing import Any
 
-from .types import Component, Keyword, Lambda, Macro, NIL, StyleValue, Symbol
+from .types import Component, Keyword, Lambda, Macro, NIL, Symbol
 from .evaluator import _eval as _raw_eval, _call_component as _raw_call_component, _expand_macro, _trampoline
 
 def _eval(expr, env):
@@ -510,19 +510,6 @@ def _render_element(tag: str, args: list, env: dict[str, Any]) -> str:
             children.append(arg)
             i += 1
 
-    # Handle :style StyleValue — convert to class and register CSS rule
-    style_val = attrs.get("style")
-    if isinstance(style_val, StyleValue):
-        from .css_registry import register_generated_rule
-        register_generated_rule(style_val)
-        # Merge into :class
-        existing_class = attrs.get("class")
-        if existing_class and existing_class is not NIL and existing_class is not False:
-            attrs["class"] = f"{existing_class} {style_val.class_name}"
-        else:
-            attrs["class"] = style_val.class_name
-        del attrs["style"]
-
     # Collect CSS classes if collector is active
     class_val = attrs.get("class")
     if class_val is not None and class_val is not NIL and class_val is not False: