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/utils/frontendUrl.js

@@ -0,0 +1,27 @@
+const { db } = require('../database/db');
+
+const getFrontendBaseUrl = async () => {
+  let base = (process.env.FRONTEND_URL || '').trim().replace(/\/$/, '');
+  if (base) return base;
+
+  try {
+    const setting = await db('app_settings')
+      .where('setting_key', 'general_site_url')
+      .select('setting_value')
+      .first();
+
+    if (setting && setting.setting_value) {
+      let val = setting.setting_value;
+      if (typeof val === 'string') {
+        try { val = JSON.parse(val); } catch (_) {}
+      }
+      if (typeof val === 'string' && val.trim()) {
+        base = val.trim().replace(/\/$/, '');
+      }
+    }
+  } catch (_) {}
+
+  return base;
+};
+
+module.exports = { getFrontendBaseUrl };