feat: draft mode, admin branding, and workflow improvements

Draft Mode:
- Events are created as drafts by default — no email sent until published
- Add "Publish & Notify Client" button with confirmation dialog
- Draft banner with yellow styling on event details page
- Draft filter tab in events list
- Gallery middleware blocks public access to draft events
- Migration 076 adds is_draft column to events table

Admin Draft Preview:
- Admins can preview draft galleries via JWT preview token (?preview=)
- "View Gallery" link on drafts auto-appends preview token

Admin & Login Page Branding:
- Admin header uses configured company logo/name from branding settings
- Login page shows configured logo instead of hardcoded PicPeak
- Respects logo_display_mode (logo_only, text_only, logo_and_text)

OG Tag Branding:
- DynamicFavicon component updates OG meta tags and page title from
  branding settings

Editable Client Email:
- Customer email is now editable after event creation in edit mode

Branding Inheritance:
- New events inherit hero logo settings (visibility, size, position)
  from global branding configuration

Share Link Full Domain URL:
- New getFrontendBaseUrl() utility with DB fallback to general_site_url
- Used in email processor and share link service

backend/src/services/emailProcessor.js

@@ -2,6 +2,7 @@ const nodemailer = require('nodemailer');
 const Handlebars = require('handlebars');
 const { db } = require('../database/db');
 const logger = require('../utils/logger');
+const { getFrontendBaseUrl } = require('../utils/frontendUrl');
 
 let transporter = null;
 let lastConfigHash = null;
@@ -161,7 +162,7 @@ async function wrapEmailHtml(htmlBody, subject, language = 'en') {
   const hoverColor = darkenColor(primaryColor, 0.15);
 
   // Build full logo URL - ensure logoUrl is a valid non-empty string
-  const frontendUrl = (process.env.FRONTEND_URL || 'http://localhost:3000').replace(/\/+$/, '');
+  const frontendUrl = (await getFrontendBaseUrl()) || 'http://localhost:3000';
   const logoPath = (typeof logoUrl === 'string' && logoUrl.trim()) ? logoUrl : '/picpeak-logo-transparent.png';
   const logoFullUrl = `${frontendUrl}${logoPath.startsWith('/') ? '' : '/'}${logoPath}`;
   logger.debug('Email logo URL:', { frontendUrl, logoPath, logoFullUrl });