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.

package.json

@@ -7,7 +7,7 @@
     "dev": " nuxt dev",
     "generate": "nuxt generate",
     "preview": "nuxt preview",
-    "postinstall": "nuxt prepare",
+    "postinstall": "patch-package && nuxt prepare",
     "test": "vitest",
     "test:run": "vitest run",
     "test:e2e": "npx playwright test",
@@ -28,6 +28,7 @@
     "@nuxt/eslint": "^1.9.0",
     "@nuxt/ui": "^4.0.0",
     "@nuxtjs/plausible": "^3.0.1",
+    "@resvg/resvg-js": "^2.6.2",
     "@slack/web-api": "^7.10.0",
     "chrono-node": "^2.8.4",
     "cloudinary": "^2.7.0",
@@ -41,6 +42,7 @@
     "oidc-provider": "^9.6.1",
     "rate-limiter-flexible": "^9.1.1",
     "resend": "^6.0.1",
+    "satori": "^0.26.0",
     "typescript": "^5.9.2",
     "vue": "^3.5.20",
     "vue-cal": "^5.0.1-rc.28",
@@ -58,6 +60,7 @@
     "@types/oidc-provider": "^9.5.0",
     "husky": "^9.1.7",
     "jsdom": "^28.1.0",
+    "patch-package": "^8.0.1",
     "vitest": "^4.0.18"
   }
 }