Badges: template controls cfg, collapsible form sections, navigation polish

- badge_template_form: fix default field visibility (location off render, pronouns/leads excluded from controls); fix duplicate QR checkboxes by removing orphan show_qr_front/back state vars; reorganize Advanced cfg_json into labeled sub-groups; make all 5 non-Advanced sections collapsible (general starts open, rest collapsed)
- print_controls: add DEFAULT_SHOWN constant so field_shown() uses explicit whitelist fallback instead of showing all fields when no controls_cfg is set
- badges config +page: add Templates navigation button in header (FileText icon)
- templates +page: add back-nav header with ArrowLeft to badges/config, Settings icon, page title

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

src/routes/events/[event_id]/(badges)/badges/[badge_id]/ae_comp__badge_print_controls.svelte

@@ -153,11 +153,16 @@ const DEFAULT_AUTH_EDITABLE = [
     'pronouns'
 ];
 
+// Default shown fields in the controls panel when the template has no explicit controls_cfg.
+// Pronouns and lead scanning are off by default — most events don't expose them.
+// WHY: prevents clutter for attendees at the badge table; events that need them must opt in via template config.
+const DEFAULT_SHOWN = ['name', 'title', 'affiliations', 'location'];
+
 /** Is this field card shown in the panel at all? trusted+edit always sees all fields. */
 function field_shown(field: string): boolean {
     if (is_trusted && is_global_edit_mode) return true;
     const cfg = template_controls_cfg;
-    if (!cfg?.shown) return true;
+    if (!cfg?.shown) return DEFAULT_SHOWN.includes(field);
     return cfg.shown.includes(field);
 }