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/types.py

@@ -303,30 +303,6 @@ class ActionDef:
         return f"<action:{self.name}({', '.join(self.params)})>"
 
 
-# ---------------------------------------------------------------------------
-# StyleValue
-# ---------------------------------------------------------------------------
-
-@dataclass(frozen=True)
-class StyleValue:
-    """A resolved CSS style produced by ``(css :flex :gap-4 :hover:bg-sky-200)``.
-
-    Generated by the style resolver. The renderer emits ``class_name`` as a
-    CSS class and registers the CSS rule for on-demand delivery.
-    """
-    class_name: str           # "sx-a3f2c1"
-    declarations: str         # "display:flex;gap:1rem"
-    media_rules: tuple = ()   # ((query, decls), ...)
-    pseudo_rules: tuple = ()  # ((selector, decls), ...)
-    keyframes: tuple = ()     # (("spin", "@keyframes spin{...}"), ...)
-
-    def __repr__(self):
-        return f"<StyleValue {self.class_name}>"
-
-    def __str__(self):
-        return self.class_name
-
-
 # ---------------------------------------------------------------------------
 # Continuation
 # ---------------------------------------------------------------------------
@@ -368,4 +344,4 @@ class _ShiftSignal(BaseException):
 # ---------------------------------------------------------------------------
 
 # An s-expression value after evaluation
-SExp = int | float | str | bool | Symbol | Keyword | Lambda | Macro | Component | Continuation | HandlerDef | RelationDef | PageDef | QueryDef | ActionDef | StyleValue | list | dict | _Nil | None
+SExp = int | float | str | bool | Symbol | Keyword | Lambda | Macro | Component | Continuation | HandlerDef | RelationDef | PageDef | QueryDef | ActionDef | list | dict | _Nil | None