feat(analytics-hubspot): modularize analytics and HubSpot integration

- Moved Google Analytics and HubSpot integration scripts to separate modules for better organization and maintainability.
- Implemented an AnalyticsManager class to handle Google Analytics initialization and privacy notice display.
- Created a HubSpotManager class to manage HubSpot widget loading and dark mode theming.
- Updated index.html to reference the new modules, improving code clarity and separation of concerns.

worklenz-frontend/public/js/analytics.js

@@ -0,0 +1,97 @@
+/**
+ * Google Analytics initialization module
+ * Handles analytics loading and privacy notices
+ */
+
+class AnalyticsManager {
+  constructor() {
+    this.isProduction = window.location.hostname === 'app.worklenz.com';
+    this.trackingId = this.isProduction ? 'G-7KSRKQ1397' : 'G-3LM2HGWEXG';
+  }
+
+  /**
+   * Initialize Google Analytics asynchronously
+   */
+  init() {
+    const loadAnalytics = () => {
+      // Load the Google Analytics script
+      const script = document.createElement('script');
+      script.async = true;
+      script.src = `https://www.googletagmanager.com/gtag/js?id=${this.trackingId}`;
+      document.head.appendChild(script);
+
+      // Initialize Google Analytics
+      window.dataLayer = window.dataLayer || [];
+      function gtag() {
+        dataLayer.push(arguments);
+      }
+      gtag('js', new Date());
+      gtag('config', this.trackingId);
+    };
+
+    // Use requestIdleCallback if available, otherwise setTimeout
+    if ('requestIdleCallback' in window) {
+      requestIdleCallback(loadAnalytics, { timeout: 2000 });
+    } else {
+      setTimeout(loadAnalytics, 1000);
+    }
+  }
+
+  /**
+   * Show privacy notice for non-production environments
+   */
+  showPrivacyNotice() {
+    const notice = document.createElement('div');
+    notice.style.cssText = `
+      position: fixed;
+      bottom: 16px;
+      right: 16px;
+      background: #222;
+      color: #f5f5f5;
+      padding: 12px 16px 10px 16px;
+      border-radius: 7px;
+      box-shadow: 0 2px 8px rgba(0,0,0,0.18);
+      z-index: 1000;
+      max-width: 320px;
+      font-family: Inter, sans-serif;
+      border: 1px solid #333;
+      font-size: 0.95rem;
+    `;
+    notice.innerHTML = `
+      <div style="margin-bottom: 6px; font-weight: 600; color: #fff; font-size: 1rem;">Analytics Notice</div>
+      <div style="margin-bottom: 8px; color: #f5f5f5;">This app uses Google Analytics for anonymous usage stats. No personal data is tracked.</div>
+      <button id="analytics-notice-btn" style="padding: 5px 14px; background: #1890ff; color: white; border: none; border-radius: 3px; cursor: pointer; font-size: 0.95rem;">Got it</button>
+    `;
+    document.body.appendChild(notice);
+
+    // Add event listener to button
+    const btn = notice.querySelector('#analytics-notice-btn');
+    btn.addEventListener('click', (e) => {
+      e.preventDefault();
+      localStorage.setItem('privacyNoticeShown', 'true');
+      notice.remove();
+    });
+  }
+
+  /**
+   * Check if privacy notice should be shown
+   */
+  checkPrivacyNotice() {
+    const isProduction = 
+      window.location.hostname === 'worklenz.com' ||
+      window.location.hostname === 'app.worklenz.com';
+    const noticeShown = localStorage.getItem('privacyNoticeShown') === 'true';
+
+    // Show notice if not in production and not shown before
+    if (!isProduction && !noticeShown) {
+      this.showPrivacyNotice();
+    }
+  }
+}
+
+// Initialize analytics when DOM is ready
+document.addEventListener('DOMContentLoaded', () => {
+  const analytics = new AnalyticsManager();
+  analytics.init();
+  analytics.checkPrivacyNotice();
+});