website: add /cloud design partners page and shared shell

- New /cloud page with signup form (email, name, company, role, message)
  posting to a Discord webhook via a TanStack Start server function on
  the Cloudflare Worker. Webhook URL read from DISCORD_WEBHOOK_URL secret.
- Extract SiteShell, SiteFooter, FAQItem from landing-page.
- Migrate /privacy, /download, /blog, /changelog, /cloud to SiteShell so
  they share header + footer with consistent width.
- Add /cloud to header and footer nav.
- Make /docs sidebar full-width; bump footer text from xs to sm.
- Add Cloudflare Workers types and ignore .dev.vars.

packages/website/src/cloud-signup.ts

@@ -0,0 +1,84 @@
+import { env } from "cloudflare:workers";
+import { createServerFn } from "@tanstack/react-start";
+
+export interface CloudSignupInput {
+  email: string;
+  name?: string;
+  company?: string;
+  role?: string;
+  message: string;
+  honeypot?: string;
+}
+
+const EMAIL_RE = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+
+function asString(v: unknown, max: number): string {
+  if (typeof v !== "string") throw new Error("expected string");
+  const trimmed = v.trim();
+  if (trimmed.length > max) throw new Error("field too long");
+  return trimmed;
+}
+
+function validate(raw: unknown): CloudSignupInput {
+  if (typeof raw !== "object" || raw === null) throw new Error("invalid input");
+  const r = raw as Record<string, unknown>;
+
+  const email = asString(r.email, 320);
+  if (!EMAIL_RE.test(email)) throw new Error("invalid email");
+
+  const message = asString(r.message, 4000);
+  if (message.length === 0) throw new Error("message required");
+
+  const name = r.name === undefined || r.name === "" ? undefined : asString(r.name, 200);
+  const company =
+    r.company === undefined || r.company === "" ? undefined : asString(r.company, 200);
+  const role = r.role === undefined || r.role === "" ? undefined : asString(r.role, 200);
+  const honeypot = typeof r.honeypot === "string" ? r.honeypot : "";
+
+  return { email, name, company, role, message, honeypot };
+}
+
+function truncate(s: string, max: number): string {
+  return s.length <= max ? s : `${s.slice(0, max - 1)}…`;
+}
+
+function buildEmbed(input: CloudSignupInput) {
+  const fields: Array<{ name: string; value: string; inline?: boolean }> = [
+    { name: "Email", value: truncate(input.email, 1024), inline: true },
+  ];
+  if (input.name) {
+    fields.push({ name: "Name", value: truncate(input.name, 1024), inline: true });
+  }
+  if (input.company) {
+    fields.push({ name: "Company", value: truncate(input.company, 1024), inline: true });
+  }
+  if (input.role) {
+    fields.push({ name: "Role", value: truncate(input.role, 1024), inline: true });
+  }
+  fields.push({ name: "Message", value: truncate(input.message, 1024) });
+
+  return {
+    title: "Paseo Cloud signup",
+    color: 0x5865f2,
+    fields,
+    timestamp: new Date().toISOString(),
+  };
+}
+
+export const submitCloudSignup = createServerFn({ method: "POST" })
+  .inputValidator(validate)
+  .handler(async ({ data }) => {
+    if (data.honeypot) return { ok: true };
+
+    const url = (env as { DISCORD_WEBHOOK_URL?: string }).DISCORD_WEBHOOK_URL;
+    if (!url) throw new Error("webhook not configured");
+
+    const res = await fetch(url, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ embeds: [buildEmbed(data)] }),
+    });
+
+    if (!res.ok) throw new Error(`webhook ${res.status}`);
+    return { ok: true };
+  });