feat(style): generate checked class tokens

Add a boring CSS/SCSS class-token surface: slhx-build discovers static class tokens from hemplate/templates/stylesheets and emits generated CssClass constants. Add CssClasses for hemplate +class/view data and migrate techdemo dynamic/effect fragments toward hemplate-owned views with DOM-aware assertions.

req: style/001

req: style/002

req: style/003

req: html_safety/002

req: view/001

req: test/005

slhx-core/tests/effect_batch.rs

@@ -1,4 +1,8 @@
-use slhx_core::{event, navigate, redirect, replace, Atom, AtomSnapshot, AtomState, BuildFingerprint, Effect, EffectBatch, Form, IntoEffect, KeyedSlot, NavigateMode, Payload, ResourceKind, SafeHtml, ScopeKey, Slot};
+use slhx_core::{
+    event, navigate, redirect, replace, Atom, AtomSnapshot, AtomState, BuildFingerprint,
+    CssClass, CssClasses, Effect, EffectBatch, Form, IntoEffect, KeyedSlot, NavigateMode, Payload,
+    ResourceKind, SafeHtml, ScopeKey, Slot,
+};
 
 #[test]
 fn effect_batch_wire_round_trips() {
@@ -88,6 +92,18 @@ fn slot_html_requires_explicit_safe_html() {
     assert_eq!(payload, Payload::Html(String::from("<strong>ok</strong>")));
 }
 
+#[test]
+fn generated_css_classes_join_for_hemplate_dynamic_class_attrs() {
+    // req: style/003
+    const CARD: CssClass = CssClass::new("work-card");
+    const SELECTED: CssClass = CssClass::new("is-selected");
+
+    let classes = CssClasses::from([CARD, SELECTED]);
+
+    assert_eq!(classes.as_str(), "work-card is-selected");
+    assert_eq!(classes.to_string(), "work-card is-selected");
+}
+
 #[test]
 fn atom_state_bootstrap_is_postcard_round_trippable() {
     let state = AtomState {