feat: enrich commerce event action from Rokt.CommerceEventType

[jaissica12]

Summary

This PR adds commerce event type enrichment to the Rokt Kit. When the core SDK populates a Rokt.CommerceEventType custom flag on new commerce event types (e.g., payment_succeeded, view_cart), the Kit reads this flag and overrides product_action.action from "unknown" to the actual event name before sending the batch to __batch_stream__.

This is the Kit-side counterpart to the core SDK PR #1269

Changes

• Added enrichCommerceEventTypes() private method to RoktKit — iterates batch events, skips non-commerce events, reads custom_flags['Rokt.CommerceEventType'], and overrides product_action.action
• Called in processBatch() before sendBatchStream() so enrichment happens just before __batch_stream__
• Safe to release independently — if the core SDK hasn't been updated yet, the custom flag is absent and enrichment is a no-op (action remains "unknown")

Testing Plan

• Added 5 unit tests in #enrichCommerceEventTypes describe block:
  • Replaces action with custom flag value for commerce events
  • Does not modify action when custom flag is absent
  • Does not modify non-commerce events (even if custom flag is present)
  • Enriches only commerce events in a mixed batch
  • Handles batch with no events
• Verified end-to-end on local playground:
  • [Forwarder] Batch sent to Kit shows action: "unknown"
  • [Rokt Kit] After enrichment shows action: "payment_succeeded"
  • MPServer batch remains action: "unknown" (unaffected)