feat: add custom branding for signing pages (#2785)

Platform-plan organisations and teams can now customise non-embed
signing pages with six brand colour tokens, a border-radius, and
a free-text custom CSS block (up to 256 KB).

- Stored on OrganisationGlobalSettings / TeamGlobalSettings;
  teams inherit from the org via brandingEnabled === null.
- CSS is sanitised on save (PostCSS) so we can inline it at SSR
  with no per-render parsing.
- Rendered via a nonce'd <style> scoped under .documenso-branded,
  using native CSS nesting so user selectors don't need scoping.
- Gated on the existing embedSigningWhiteLabel claim (or
  self-hosted) — reuses the embed white-label decision.

apps/remix/app/routes/_recipient+/d.$token+/_index.tsx

@@ -2,6 +2,7 @@ import { getOptionalSession } from '@documenso/auth/server/lib/utils/get-session
 import { EnvelopeRenderProvider } from '@documenso/lib/client-only/providers/envelope-render-provider';
 import { useOptionalSession } from '@documenso/lib/client-only/providers/session';
 import { AppError, AppErrorCode } from '@documenso/lib/errors/app-error';
+import { loadRecipientBrandingByTeamId } from '@documenso/lib/server-only/branding/load-recipient-branding';
 import { getEnvelopeForDirectTemplateSigning } from '@documenso/lib/server-only/envelope/get-envelope-for-direct-template-signing';
 import { getTemplateByDirectLinkToken } from '@documenso/lib/server-only/template/get-template-by-direct-link-token';
 import { DocumentAccessAuth } from '@documenso/lib/types/document-auth';
@@ -20,6 +21,8 @@ import { DocumentSigningAuthProvider } from '~/components/general/document-signi
 import { DocumentSigningPageViewV2 } from '~/components/general/document-signing/document-signing-page-view-v2';
 import { DocumentSigningProvider } from '~/components/general/document-signing/document-signing-provider';
 import { EnvelopeSigningProvider } from '~/components/general/document-signing/envelope-signing-provider';
+import { RecipientBranding } from '~/components/general/recipient-branding';
+import { useCspNonce } from '~/utils/nonce';
 import { superLoaderJson, useSuperLoaderData } from '~/utils/super-json-loader';
 
 import type { Route } from './+types/_index';
@@ -125,6 +128,7 @@ export async function loader(loaderArgs: Route.LoaderArgs) {
     },
     select: {
       internalVersion: true,
+      teamId: true,
     },
   });
 
@@ -132,12 +136,17 @@ export async function loader(loaderArgs: Route.LoaderArgs) {
     throw new Response('Not Found', { status: 404 });
   }
 
+  const branding = await loadRecipientBrandingByTeamId({
+    teamId: directEnvelope.teamId,
+  });
+
   if (directEnvelope.internalVersion === 2) {
     const payloadV2 = await handleV2Loader(loaderArgs);
 
     return superLoaderJson({
       version: 2,
       payload: payloadV2,
+      branding,
     } as const);
   }
 
@@ -146,17 +155,20 @@ export async function loader(loaderArgs: Route.LoaderArgs) {
   return superLoaderJson({
     version: 1,
     payload: payloadV1,
+    branding,
   } as const);
 }
 
 export default function DirectTemplatePage() {
   const data = useSuperLoaderData<typeof loader>();
+  const cspNonce = useCspNonce();
 
-  if (data.version === 2) {
-    return <DirectSigningPageV2 data={data.payload} />;
-  }
-
-  return <DirectSigningPageV1 data={data.payload} />;
+  return (
+    <>
+      <RecipientBranding branding={data.branding} cspNonce={cspNonce} />
+      {data.version === 2 ? <DirectSigningPageV2 data={data.payload} /> : <DirectSigningPageV1 data={data.payload} />}
+    </>
+  );
 }
 
 const DirectSigningPageV1 = ({ data }: { data: Awaited<ReturnType<typeof handleV1Loader>> }) => {