feat: podman.live Caddy + social link previews

infra/Caddyfile: add podman.live + www.podman.live (serve app + proxy /api),
so the domain is durable in the canonical config (not just a manual edit).
index.html: Open Graph + Twitter Card meta (title, description, og:image) so
sharing www.podman.live renders a rich preview. Adds a 1200x630 og.png card
(generated from og.svg) under public/.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

infra/Caddyfile

@@ -22,3 +22,19 @@ lk.165-22-129-249.sslip.io {
 		}
 	}
 }
+
+podman.live, www.podman.live {
+	route {
+		handle /api/* {
+			reverse_proxy 127.0.0.1:8787
+		}
+
+		handle /health {
+			reverse_proxy 127.0.0.1:8787
+		}
+
+		root * /var/www/podman
+		try_files {path} /index.html
+		file_server
+	}
+}