feat: redirect vite.plus vanity domain to installer scripts

Point the newly-attached vite.plus apex domain at the Vite+ install
scripts so `curl https://vite.plus | sh` and `irm https://vite.plus/ps1
| iex` work as install entry points:

  https://vite.plus     -> 302 https://viteplus.dev/install.sh
  https://vite.plus/ps1 -> 302 https://viteplus.dev/install.ps1

Implemented as a host-based middleware mirroring the existing
01.redirect-to-custom-domain pattern. Only the vite.plus apex host is
matched; the canonical setup host, the legacy host, and localhost fall
through untouched. Any non-/ps1 path defaults to install.sh.

Author: fengmk2

middleware/02.redirect-vite-plus.ts

@@ -0,0 +1,20 @@
+import { defineMiddleware } from "void";
+
+// The vite.plus vanity domain exists purely as an installer entry point:
+//   curl https://vite.plus     | sh   -> shell installer
+//   irm  https://vite.plus/ps1 | iex  -> PowerShell installer
+const INSTALL_HOST = "vite.plus";
+const INSTALL_SH = "https://viteplus.dev/install.sh";
+const INSTALL_PS1 = "https://viteplus.dev/install.ps1";
+
+export function buildViteplusRedirect(host: string | undefined, requestUrl: string): string | null {
+  if (host !== INSTALL_HOST) return null;
+  const path = new URL(requestUrl).pathname.replace(/\/+$/, "");
+  return path === "/ps1" ? INSTALL_PS1 : INSTALL_SH;
+}
+
+export default defineMiddleware(async (c, next) => {
+  const target = buildViteplusRedirect(c.req.header("host"), c.req.url);
+  if (target) return c.redirect(target, 302);
+  await next();
+});

tests/redirect-vite-plus.test.ts

@@ -0,0 +1,50 @@
+import { describe, expect, it } from "vite-plus/test";
+import { buildViteplusRedirect } from "../middleware/02.redirect-vite-plus";
+
+describe("buildViteplusRedirect", () => {
+  it("redirects the bare domain to the shell installer", () => {
+    expect(buildViteplusRedirect("vite.plus", "https://vite.plus/")).toBe(
+      "https://viteplus.dev/install.sh",
+    );
+  });
+
+  it("redirects /ps1 to the PowerShell installer", () => {
+    expect(buildViteplusRedirect("vite.plus", "https://vite.plus/ps1")).toBe(
+      "https://viteplus.dev/install.ps1",
+    );
+  });
+
+  it("tolerates a trailing slash on /ps1", () => {
+    expect(buildViteplusRedirect("vite.plus", "https://vite.plus/ps1/")).toBe(
+      "https://viteplus.dev/install.ps1",
+    );
+  });
+
+  it("redirects any other path to the shell installer", () => {
+    expect(buildViteplusRedirect("vite.plus", "https://vite.plus/anything")).toBe(
+      "https://viteplus.dev/install.sh",
+    );
+  });
+
+  it("ignores query strings when picking the target", () => {
+    expect(buildViteplusRedirect("vite.plus", "https://vite.plus/?ref=docs")).toBe(
+      "https://viteplus.dev/install.sh",
+    );
+  });
+
+  it("returns null for the canonical download host", () => {
+    expect(buildViteplusRedirect("setup.viteplus.dev", "https://setup.viteplus.dev/")).toBeNull();
+  });
+
+  it("returns null for the legacy host (handled by its own middleware)", () => {
+    expect(buildViteplusRedirect("vp-setup.void.app", "https://vp-setup.void.app/")).toBeNull();
+  });
+
+  it("returns null for localhost during dev", () => {
+    expect(buildViteplusRedirect("localhost:5173", "http://localhost:5173/ps1")).toBeNull();
+  });
+
+  it("returns null when the host header is missing", () => {
+    expect(buildViteplusRedirect(undefined, "https://vite.plus/")).toBeNull();
+  });
+});