feat(build): emit checked param tokens

Generate ParamName constants for handle data parameters so public code can refer to checked param metadata instead of stringly typed names.

req: codegen/003

slhx-core/tests/effect_batch.rs

@@ -1,7 +1,7 @@
 use slhx_core::{
     event, navigate, redirect, replace, Atom, AtomSnapshot, AtomState, BuildFingerprint,
     ComponentRef, CssClass, CssClasses, Effect, EffectBatch, Form, Handle, IntoEffect, KeyedSlot,
-    NavigateMode, Payload, ResourceKind, SafeHtml, ScopeKey, Slot,
+    NavigateMode, ParamName, Payload, ResourceKind, SafeHtml, ScopeKey, Slot,
 };
 
 #[test]
@@ -93,6 +93,14 @@ fn slot_html_requires_explicit_safe_html() {
     assert_eq!(payload, Payload::Html(String::from("<strong>ok</strong>")));
 }
 
+#[test]
+fn param_names_format_generated_param_names() {
+    // req: codegen/003
+    let param = ParamName::new("todo_id");
+    assert_eq!(param.as_str(), "todo_id");
+    assert_eq!(param.to_string(), "todo_id");
+}
+
 #[test]
 fn component_refs_format_generated_component_names() {
     // req: component/003