Support separate header logo images for light and dark themes (#36362)

Server Pro/CE admins can set a custom header logo via OVERLEAF_HEADER_IMAGE_URL,
but the same image is used for both the light and dark navbar themes. A logo
with good contrast on one background can be hard to see on the other (e.g. a
dark logo on the dark dashboard navbar).

Add two optional env vars, OVERLEAF_HEADER_IMAGE_URL_LIGHT and
OVERLEAF_HEADER_IMAGE_URL_DARK, each falling back to OVERLEAF_HEADER_IMAGE_URL
when unset, so existing configurations are unaffected. The light/dark fallback is
resolved server-side and exposed to the frontend as customLogo (light-effective)
and customLogoDark (dark-effective); the two theme-aware navbars (project
dashboard and library) pick between them using the existing overall-theme hook,
so the logo tracks both the user's theme setting and live OS theme changes.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
GitOrigin-RevId: 587a5679c650717cba6251e6d612146f434e8730

services/web/app/views/layout-react.pug

@@ -22,7 +22,8 @@ block append meta
 		name='ol-navbar'
 		data-type='json'
 		content={
-			customLogo: settings.nav.custom_logo,
+			customLogo: settings.nav.custom_logo_light || settings.nav.custom_logo,
+			customLogoDark: settings.nav.custom_logo_dark || settings.nav.custom_logo,
 			title: nav.title,
 			canDisplayAdminMenu,
 			canDisplayAdminRedirect,

services/web/app/views/layout/navbar-marketing.pug

@@ -9,12 +9,13 @@ nav.navbar.navbar-default.navbar-main.navbar-expand-lg(
 )
 	.container-fluid.navbar-container
 		.navbar-header
+			- var customLogo = settings.nav.custom_logo_light || settings.nav.custom_logo
 			a.navbar-brand(href='/' aria-label=settings.appName)
-				if settings.nav.custom_logo
-					.navbar-logo(style=`background-image:url("${settings.nav.custom_logo}")`)
+				if customLogo
+					.navbar-logo(style=`background-image:url("${customLogo}")`)
 				if nav.title
 					.navbar-title #{nav.title}
-				if !nav.title && !settings.nav.custom_logo
+				if !nav.title && !customLogo
 					.navbar-logo
 
 			- var enableUpgradeButton = projectDashboardReact && usersBestSubscription && (usersBestSubscription.type === 'free' || usersBestSubscription.type === 'standalone-ai-add-on')

services/web/frontend/js/features/project-list/components/project-list-ds-nav.tsx

@@ -78,6 +78,11 @@ export function ProjectListDsNav() {
       <SystemMessages />
       <DefaultNavbar
         {...navbarProps}
+        customLogo={
+          activeOverallTheme === 'dark'
+            ? navbarProps.customLogoDark
+            : navbarProps.customLogo
+        }
         overleafLogo={
           activeOverallTheme === 'dark' ? overleafLogoDark : overleafLogo
         }

services/web/frontend/js/shared/components/types/default-navbar-metadata.ts

@@ -5,6 +5,7 @@ import type {
 
 export type DefaultNavbarMetadata = {
   customLogo?: string
+  customLogoDark?: string
   title?: string
   canDisplayAdminMenu: boolean
   canDisplayAdminRedirect: boolean