Remove EmailBranding component and fix Puck sidebar scroll

- Remove EmailBranding from Puck editor (branding auto-shows for free tier)
- Fix sidebar scroll in email template editor with single scrollbar
- Fix logo data URL format in email_renderer.py

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/settings/SystemEmailTemplates.tsx

@@ -5,7 +5,7 @@
  * (welcome, appointment confirmations, reminders, etc.) using a Puck editor.
  */
 
-import React, { useState, useCallback, useMemo } from 'react';
+import React, { useState, useCallback, useMemo, useEffect } from 'react';
 import { useTranslation } from 'react-i18next';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { Puck, Render } from '@measured/puck';
@@ -103,6 +103,36 @@ const SystemEmailTemplates: React.FC = () => {
   // Get email editor config
   const editorConfig = getEmailEditorConfig();
 
+  // Fix Puck sidebar scrolling when editor is open
+  useEffect(() => {
+    if (!editingTemplate) return;
+
+    const fixSidebars = () => {
+      // Target only the main left/right sidebar containers
+      const leftSidebar = document.querySelector('[class*="Sidebar--left"]') as HTMLElement;
+      const rightSidebar = document.querySelector('[class*="Sidebar--right"]') as HTMLElement;
+
+      [leftSidebar, rightSidebar].forEach((sidebar) => {
+        if (!sidebar) return;
+
+        // Make the main sidebar scroll
+        sidebar.style.maxHeight = 'calc(100vh - 300px)';
+        sidebar.style.overflowY = 'auto';
+
+        // Remove overflow from inner sections so only the main sidebar scrolls
+        const innerSections = sidebar.querySelectorAll('[class*="SidebarSection"]');
+        innerSections.forEach((section) => {
+          (section as HTMLElement).style.overflow = 'visible';
+          (section as HTMLElement).style.maxHeight = 'none';
+        });
+      });
+    };
+
+    // Run after Puck renders
+    const timer = setTimeout(fixSidebars, 200);
+    return () => clearTimeout(timer);
+  }, [editingTemplate]);
+
   // Fetch all email templates
   const { data: templates = [], isLoading } = useQuery<SystemEmailTemplate[]>({
     queryKey: ['system-email-templates'],
@@ -281,6 +311,7 @@ const SystemEmailTemplates: React.FC = () => {
           puck_data: editorData,
         },
       });
+
       setPreviewSubject(preview.subject);
       setPreviewHtml(preview.html);
       setPreviewText(preview.text);