migrate from astro+netlify to tanstack start + self-hosted

Replace the Astro static site with a TanStack Start (Bun runtime) app and
add Dockerfile + compose files so the site can be served from home-main-2
behind the home-reverse-proxy-1 Caddy instead of Netlify. CI workflow
rewritten to build a container image and SSH-deploy to the home host.

vite.config.ts

@@ -0,0 +1,20 @@
+import tailwindcss from "@tailwindcss/vite";
+import { tanstackStart } from "@tanstack/react-start/plugin/vite";
+import viteReact from "@vitejs/plugin-react";
+import { nitro } from "nitro/vite";
+import { defineConfig } from "vite";
+
+export default defineConfig({
+	resolve: {
+		tsconfigPaths: true,
+		dedupe: ["react", "react-dom"],
+	},
+	plugins: [
+		tailwindcss(),
+		tanstackStart(),
+		nitro({
+			preset: "bun",
+		}),
+		viteReact(),
+	],
+});