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/primitives_stdlib.py

@@ -89,37 +89,6 @@ def prim_strip_tags(s: str) -> str:
     return re.sub(r"<[^>]+>", "", s)
 
 
-# ---------------------------------------------------------------------------
-# stdlib.style
-# ---------------------------------------------------------------------------
-
-@register_primitive("css")
-def prim_css(*args: Any) -> Any:
-    """``(css :flex :gap-4 :hover:bg-sky-200)`` → StyleValue."""
-    from .types import Keyword
-    from .style_resolver import resolve_style
-    atoms = tuple(
-        (a.name if isinstance(a, Keyword) else str(a))
-        for a in args if a is not None and a is not NIL and a is not False
-    )
-    if not atoms:
-        return NIL
-    return resolve_style(atoms)
-
-
-@register_primitive("merge-styles")
-def prim_merge_styles(*styles: Any) -> Any:
-    """``(merge-styles style1 style2)`` → merged StyleValue."""
-    from .types import StyleValue
-    from .style_resolver import merge_styles
-    valid = [s for s in styles if isinstance(s, StyleValue)]
-    if not valid:
-        return NIL
-    if len(valid) == 1:
-        return valid[0]
-    return merge_styles(valid)
-
-
 # ---------------------------------------------------------------------------
 # stdlib.debug
 # ---------------------------------------------------------------------------