Fix template formatters: expose c.fields by name not ID

c.fields was keyed by generated field IDs, so c.fields?.resistance
was always undefined. Now fields are remapped by name before being
passed to formatters, so the documented API works as expected.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/app.mjs

@@ -90,10 +90,23 @@ function compile_templates() {
 	}
 }
 
+// Build a version of the component where c.fields is keyed by field name
+// instead of field ID, so formatters can use c.fields?.resistance etc.
+function named_fields_comp(comp) {
+	const fields = {};
+	for (const [fid, val] of Object.entries(comp.fields ?? {})) {
+		const def = field_by_id(fid);
+		if (def) { fields[def.name] = val; }
+	}
+	return { ...comp, fields };
+}
+
 function component_display_name(comp) {
+	if (!compiled_formatters.length) return comp.name;
+	const c = named_fields_comp(comp);
 	for (const { fn } of compiled_formatters) {
 		try {
-			const result = fn(comp);
+			const result = fn(c);
 			if (result != null && result !== '') return String(result);
 		} catch (_) {
 			// formatter threw — skip it
@@ -609,7 +622,7 @@ function update_tmpl_preview() {
 	try {
 		// eslint-disable-next-line no-new-func
 		const fn = new Function('c', `"use strict"; return (${formatter_str})(c);`);
-		const result = fn(sample);
+		const result = fn(named_fields_comp(sample));
 		preview_el.textContent = result != null ? String(result) : `null — falls back to "${sample.name}"`;
 	} catch (err) {
 		preview_el.textContent = `Error: ${err.message}`;