Feat: White-label web UI branding for subpath deployments

When the web remote desktop is mounted under another domain's subpath
(YAMA_WEB_BASE_PATH non-empty), read the product title from
YAMA_WEB_BRAND_NAME, substitute it for the SimpleRemoter titles and
PWA manifest name, and strip the security notice and website links.
The brand name is JSON- and HTML-escaped so operator input can't
produce malformed output. Served from the domain root, the official
SimpleRemoter branding is left unchanged.

Co-Authored-By: deepseek-v4-pro

server/go/cmd/main.go

@@ -998,6 +998,14 @@ func main() {
 	if basePath != "" {
 		log.Info("Serving web UI under base path %q (subpath deployment)", basePath)
 	}
+	// White-label title: when the web UI is mounted under another domain
+	// (basePath != ""), replace the SimpleRemoter branding with this name.
+	// YAMA_WEB_BRAND_NAME is human-editable; empty falls back to the base
+	// path's last segment (e.g. "/remoter" → "Remoter").
+	brandName := strings.TrimSpace(os.Getenv("YAMA_WEB_BRAND_NAME"))
+	if brandName != "" {
+		log.Info("White-label web UI title %q (YAMA_WEB_BRAND_NAME)", brandName)
+	}
 	// SSO: an optional detector bridges an already-authenticated portal
 	// session into a YAMA web session via /sso — but only for portal
 	// administrators. Any other portal role (viewer, unknown) still has to
@@ -1017,6 +1025,7 @@ func main() {
 		LoginUserLimit:    wsauth.NewRateLimiter(5, 15*time.Minute),
 		TrustForwardedFor: trustProxy,
 		BasePath:          basePath,
+		BrandName:         brandName,
 		SSO:               ssoDetector,
 	}