feat: estimates on the homepage, monthly booking on the freelance page

The homepage showed a price list per case, including a day rate. Buyers of
a result need a way to a price, not rates: each case now shows three steps
to an estimate, one line for orientation and a button that opens the
contact message with that topic chosen.

The developer case is booked by the month, not by the day. The day rate is
gone; the freelance page has the booking terms: 100 EUR per hour, fixed
days of the week agreed for one month at a time, an example month, monthly
invoice, two weeks notice to the end of a month.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/components/home/TopicButton.tsx

@@ -0,0 +1,19 @@
+"use client";
+
+import * as React from "react";
+import { Button } from "@/src/components/Button";
+import { chooseContactTopic } from "./contactTopic";
+
+/** A call to action that jumps to the contact section with a topic already chosen. */
+export const TopicButton: React.FC<{
+  topic: string;
+  children: React.ReactNode;
+}> = ({ topic, children }) => (
+  <Button
+    href="#contact"
+    size="large"
+    onClick={() => chooseContactTopic(topic)}
+  >
+    {children}
+  </Button>
+);