feat(core): format handles for templates

Implement Display for generated Handle<T> values and migrate example view data to carry handles directly instead of raw handle id numbers for dynamic handle attributes.

req: public_api/001

req: public_api/002

slhx-core/tests/effect_batch.rs

@@ -1,7 +1,7 @@
 use slhx_core::{
     event, navigate, redirect, replace, Atom, AtomSnapshot, AtomState, BuildFingerprint,
-    CssClass, CssClasses, Effect, EffectBatch, Form, IntoEffect, KeyedSlot, NavigateMode, Payload,
-    ResourceKind, SafeHtml, ScopeKey, Slot,
+    CssClass, CssClasses, Effect, EffectBatch, Form, Handle, IntoEffect, KeyedSlot, NavigateMode,
+    Payload, ResourceKind, SafeHtml, ScopeKey, Slot,
 };
 
 #[test]
@@ -93,6 +93,12 @@ fn slot_html_requires_explicit_safe_html() {
     assert_eq!(payload, Payload::Html(String::from("<strong>ok</strong>")));
 }
 
+#[test]
+fn generated_handles_format_for_hemplate_dynamic_handle_attrs() {
+    // req: public_api/001 req: public_api/002
+    assert_eq!(Handle::<()>::new(42).to_string(), "42");
+}
+
 #[test]
 fn generated_css_classes_join_for_hemplate_dynamic_class_attrs() {
     // req: style/003