feat(docs): add documentation site and demo features

- Introduced a new documentation site for Cursor BYOK using Next.js and Fumadocs.
- Added a product demo page with a corresponding Vite configuration.
- Implemented a demo API to simulate LLM calls and responses.
- Enhanced the Makefile to include new build and development commands for the documentation.
- Updated package.json scripts for building and running the documentation site.
- Created various components and layouts for the documentation structure, including blog and user documentation sections.
- Added styling for the new components and layouts to ensure a cohesive design.
- Included a README and other necessary files for local development and deployment.

apps/docs/lib/source.ts

@@ -0,0 +1,51 @@
+import { loader } from 'fumadocs-core/source';
+import { lucideIconsPlugin } from 'fumadocs-core/source/lucide-icons';
+import { docsContentRoute, docsImageRoute, docsRoute } from './shared';
+import { defineDocs } from 'fumadocs-mdx/macro';
+import { metaSchema, pageSchema } from 'fumadocs-core/source/schema';
+
+const docs = defineDocs({
+  dir: 'content/docs',
+  docs: {
+    schema: pageSchema,
+    postprocess: {
+      includeProcessedMarkdown: true,
+    },
+  },
+  meta: {
+    schema: metaSchema,
+  },
+});
+
+// See https://fumadocs.dev/docs/headless/source-api for more info
+export const source = loader({
+  baseUrl: docsRoute,
+  source: docs.toFumadocsSource(),
+  plugins: [lucideIconsPlugin()],
+});
+
+export function getPageImageUrl(page: (typeof source)['$inferPage']) {
+  const segments = [...page.slugs, 'image.png'];
+
+  return {
+    segments,
+    url: '/' + [page.locale, ...docsImageRoute.split('/'), ...segments].filter(Boolean).join('/'),
+  };
+}
+
+export function getPageMarkdownUrl(page: (typeof source)['$inferPage']) {
+  const segments = [...page.slugs, 'content.md'];
+
+  return {
+    segments,
+    url: '/' + [page.locale, ...docsContentRoute.split('/'), ...segments].filter(Boolean).join('/'),
+  };
+}
+
+export async function getLLMText(page: (typeof source)['$inferPage']) {
+  const processed = await page.data.getText('processed');
+
+  return `# ${page.data.title} (${page.url})
+
+${processed}`;
+}