Disable analytics in dev env, redirect to edit page after event update

- Skip loading /stats/script.js and /assets/perf.js when data-env=dev
- Add data-env="{{ app.environment }}" to body tag
- Redirect to edit event page instead of events list after saving

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

assets/modules/cookie-consent.js

@@ -18,6 +18,10 @@ function loadAnalytics() {
         return
     }
 
+    if (document.body.dataset.env === 'dev') {
+        return
+    }
+
     const script = document.createElement('script')
     script.defer = true
     script.src = '/stats/script.js'