Self hosted domain redirect (#756)

* Integration pages from Notion

* Self hosted domain redirect

* Refactor root-redirect middleware and update 404 page layout

- Simplified the `root-redirect.js` middleware by removing the specific route checks, allowing for a more general redirect based on the `self_hosted` feature flag.
- Updated the 404 error page in `[...all].vue` by removing the unnecessary `NuxtLayout` wrapper and replacing `NuxtLink` with a custom `UButton` for navigation, enhancing the overall layout and user experience.

These changes aim to streamline the redirect logic and improve the presentation of the 404 error page.

* Refactor feature flag handling and update middleware

- Updated the condition in `Navbar.vue` to correctly evaluate the feature flags for rendering the AI form builder link.
- Removed the `feature-flags.global.js` middleware as it was no longer needed, streamlining the middleware structure.
- Enhanced the `root-redirect.js` middleware to utilize `h3`'s `sendRedirect` for server-side redirection, improving the redirect logic.
- Modified the `ai-form-builder.vue` page to include the new `root-redirect` middleware, ensuring proper redirection based on feature flags.

These changes aim to improve the handling of feature flags and redirection logic, enhancing the overall application flow.

---------

Co-authored-by: Julien Nahum <julien@nahum.net>

client/pages/integrations/[slug].vue

@@ -85,7 +85,7 @@ defineRouteRules({
 })
 definePageMeta({
   stickyNavbar: true,
-  middleware: ["self-hosted"]
+  middleware: ['root-redirect','self-hosted']
 })
 
 useOpnSeoMeta({

client/pages/integrations/index.vue

@@ -174,7 +174,7 @@ defineRouteRules({
 })
 definePageMeta({
   stickyNavbar: true,
-  middleware: ["self-hosted"]
+  middleware: ['root-redirect','self-hosted']
 })
 
 const crisp = useCrisp()