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/app/global.css

@@ -0,0 +1,16 @@
+@import 'tailwindcss';
+@import 'fumadocs-ui/css/neutral.css';
+@import 'fumadocs-ui/css/preset.css';
+
+:root {
+  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+}
+
+html {
+  scrollbar-gutter: stable;
+}
+
+html > body[data-scroll-locked] {
+  margin-right: 0 !important;
+  --removed-body-scroll-bar-size: 0px !important;
+}