Add /talk booking page with cal.com inline embed

The gift PDF's closing CTA promises a conversation, so it needs a
landing page to point to. Kept separate from /gift-thanks since the
PDF can be read/forwarded independent of any signup on this site.

layouts/partials/cal-embed.html

@@ -0,0 +1,19 @@
+<div id="cal-inline" class="cal-embed"></div>
+<script type="text/javascript">
+  (function (C, A, L) { let p = function (a, ar) { a.q.push(ar); }; let d = C.document; C.Cal = C.Cal || function () { let cal = C.Cal; let ar = arguments; if (!cal.loaded) { cal.ns = {}; cal.q = cal.q || []; d.head.appendChild(d.createElement("script")).src = A; cal.loaded = true; } if (ar[0] === L) { const api = function () { p(api, arguments); }; const namespace = ar[1]; api.q = api.q || []; if (typeof namespace === "string") { cal.ns[namespace] = cal.ns[namespace] || api; p(cal.ns[namespace], ar); p(cal, ["initNamespace", namespace]); } else p(cal, ar); return; } p(cal, ar); }; })(window, "https://app.cal.com/embed/embed.js", "init");
+  Cal("init", "talk", { origin: "https://cal.com" });
+  Cal.ns.talk("inline", {
+    elementOrSelector: "#cal-inline",
+    calLink: "{{ . }}",
+    config: { layout: "month_view" },
+  });
+  Cal.ns.talk("ui", {
+    theme: "dark",
+    cssVarsPerTheme: {
+      light: { "cal-brand": "#007f73" },
+      dark: { "cal-brand": "#2dd4c4" },
+    },
+    hideEventTypeDetails: false,
+    layout: "month_view",
+  });
+</script>