📈 Set PostHog $insert_id on transactional events for backend dedupe

Auto-assign $insert_id = {event}_{transaction_id} inside useLogEvent so
frontend-fired purchase/subscribe/start_trial/begin_checkout events dedupe
against the backend posthog-node counterpart that tracks the same txn.
Also rename the stray payment_id key in the book-list begin_checkout call
so it actually carries transaction_id and picks up the new behavior.

Author: williamchong

composables/use-logger.ts

@@ -167,6 +167,10 @@ export function useLogEvent(eventName: string, eventParams: EventParams = {}) {
           posthogParams.nft_class_ids = classIds.join(',')
         }
       }
+      // Dedupe against the backend-fired counterpart (posthog-node) for the same transaction.
+      if (typeof eventParams.transaction_id === 'string' && eventParams.transaction_id) {
+        posthogParams.$insert_id = `${eventName}_${eventParams.transaction_id}`
+      }
       posthog.capture(eventName, { app: '3ook', ...posthogParams })
     }
     catch (error) {

pages/list.vue

@@ -177,7 +177,7 @@ async function handleCheckoutButtonClick() {
         ...getAnalyticsParameters({ utmSource: '3ook-list' }),
       },
     )
-    useLogEvent('begin_checkout', { payment_id: paymentId })
+    useLogEvent('begin_checkout', { transaction_id: paymentId })
     await navigateTo(url, { external: true })
   }
   catch (error) {