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/index.vue

@@ -117,6 +117,33 @@ definePageMeta({
   layout: "default",
 });
 
+const runtimeConfig = useRuntimeConfig();
+const siteUrl = (runtimeConfig.public.appUrl || "").replace(/\/$/, "");
+
+useSiteMeta({
+  title: "Ghost Guild",
+  bareTitle: true,
+  description:
+    "Ghost Guild is where game developers explore cooperative models. Membership, events, and resources for people figuring it out together. Pay what you can.",
+});
+
+useHead({
+  script: [
+    {
+      type: "application/ld+json",
+      innerHTML: JSON.stringify({
+        "@context": "https://schema.org",
+        "@type": "Organization",
+        name: "Ghost Guild",
+        url: siteUrl || "https://ghostguild.org",
+        logo: `${siteUrl || "https://ghostguild.org"}/og/default.png`,
+        description:
+          "A membership community for game developers exploring cooperative models. A program of Baby Ghosts, a Canadian non-profit.",
+      }),
+    },
+  ],
+});
+
 const { data: events } = await useFetch("/api/events", {
   query: { limit: 4, upcoming: true },
   default: () => [],