Add Quickstart tab to docs page and update all Get Started links

- Added new Quickstart tab next to Overview and Integrations in docs navigation
- Created new quickstart page at /docs/quickstart/
- Removed quickstart section from Overview tab sidebar
- Updated all 'Get Started' buttons on home page to point to /docs/quickstart/
- Updated Local Development quickstart arrow to point to /docs/quickstart/
- Added quickstart to mobile navigation dropdown

Author: NicholasKissel

website/src/app/(v2)/(marketing)/(index)/sections/CTASection.tsx

@@ -0,0 +1,21 @@
+import { faNodeJs, faReact, faNextjs, faCloudflare } from "@rivet-gg/icons";
+
+# Quickstart
+
+Get started with Rivet in minutes. Choose your preferred framework or runtime to begin building with actors.
+
+<CardGroup cols={2}>
+<Card title="Node.js & Bun Quickstart" href="/docs/actors/quickstart/backend" icon={faNodeJs}>
+  Set up actors with Node.js, Bun, and web frameworks
+</Card>
+<Card title="React Quickstart" href="/docs/actors/quickstart/react" icon={faReact}>
+  Build real-time React applications with actors
+</Card>
+<Card title="Next.js Quickstart" href="/docs/actors/quickstart/next-js" icon={faNextjs}>
+  Build server-rendered Next.js experiences backed by actors
+</Card>
+<Card title="Cloudflare Workers Quickstart" href="/docs/actors/quickstart/cloudflare-workers" icon={faCloudflare}>
+  Deploy actors on Cloudflare Workers with zero infrastructure
+</Card>
+</CardGroup>
+