[docs]: explain how to build your own workflow handler (vercel#50)

* wip

* almost good

* Update meta.json

* use mermaid diagram

* sdk -> dev kit

* fixes

* security explanation

* Update runtime-adapters.mdx

* move under how it works

* update how workflow build works

* fix file filtering + remove component 3

* dedup http handler info

* merge sections

* explain difference between bun framework and runtime

* runtime adapter -> framework integration

* framework integration

* bunfig instructions

* Pranay's edits

* Refactor to 2 pages

* Improve framework integrations doc

---------

Co-authored-by: Pranay Prakash <pranay.gp@gmail.com>

Author: RhysSullivan

docs/components/mermaid.tsx

@@ -0,0 +1,61 @@
+'use client';
+
+import { useTheme } from 'next-themes';
+import { use, useEffect, useId, useState } from 'react';
+
+export function Mermaid({ chart }: { chart: string }) {
+  const [mounted, setMounted] = useState(false);
+
+  useEffect(() => {
+    setMounted(true);
+  }, []);
+
+  if (!mounted) return;
+  return <MermaidContent chart={chart} />;
+}
+
+const cache = new Map<string, Promise<unknown>>();
+
+function cachePromise<T>(
+  key: string,
+  setPromise: () => Promise<T>
+): Promise<T> {
+  const cached = cache.get(key);
+  if (cached) return cached as Promise<T>;
+
+  const promise = setPromise();
+  cache.set(key, promise);
+  return promise;
+}
+
+function MermaidContent({ chart }: { chart: string }) {
+  const id = useId();
+  const { resolvedTheme } = useTheme();
+  const { default: mermaid } = use(
+    cachePromise('mermaid', () => import('mermaid'))
+  );
+
+  mermaid.initialize({
+    startOnLoad: false,
+    securityLevel: 'loose',
+    fontFamily: 'inherit',
+    themeCSS: 'margin: 1.5rem auto 0;',
+    theme: resolvedTheme === 'dark' ? 'dark' : 'default',
+  });
+
+  const { svg, bindFunctions } = use(
+    cachePromise(`${chart}-${resolvedTheme}`, () => {
+      return mermaid.render(id, chart.replaceAll('\\n', '\n'));
+    })
+  );
+
+  return (
+    <div
+      ref={(container) => {
+        if (container) bindFunctions?.(container);
+      }}
+      // biome-ignore lint/security/noDangerouslySetInnerHtml: Matching fumadocs + is only running trusted input from mdx files
+      dangerouslySetInnerHTML={{ __html: svg }}
+    />
+  );
+}