feat(seo): site meta composable + Open Graph image generation

Adds `useSiteMeta()` composable that wraps useSeoMeta with site defaults
(title template, canonical URL, og/twitter image, og:site_name) and
absolute-URL handling via runtimeConfig.public.appUrl.

Adds /og/events/[slug].png route that renders per-event OG images via
satori + @resvg/resvg-js, cached on disk by slug + updatedAt. Bundles
Brygada 1918 + Commit Mono fonts as server assets, ships a fallback
default.png, and patches @shuding/opentype.js via patch-package.

Converts ~25 pages from useHead to useSiteMeta and adds noindex on
private/auth/admin pages.

app/pages/members/[id].vue

@@ -276,14 +276,10 @@ onUnmounted(() => {
   pageBreadcrumbTitle.value = "";
 });
 
-// Page head
-useHead({
-  title: computed(() =>
-    member.value
-      ? `${member.value.name} — Ghost Guild`
-      : "Member Profile — Ghost Guild",
-  ),
-});
+useSiteMeta(() => ({
+  title: member.value ? member.value.name : "Member Profile",
+  noindex: true,
+}));
 </script>
 
 <style scoped>