feat: capture UTM params from page views and forward to selectPlacements

[alexs-mparticle]

Summary

• Adds captureUtmParams() to pageViewStorage.ts — reads the 5 standard UTM params (utm_source, utm_medium, utm_campaign, utm_term, utm_content) from window.location.search and stores them in localStorage under the mp-rokt-kit namespace (first-touch-wins)
• Forwards captured UTMs to Rokt as page_view_attributes on every selectPlacements call; field is omitted entirely when no UTMs were seen this session
• Clears stored UTMs on SESSION_END, consistent with how pageViews is cleared

Design decisions

• First touch wins: UTMs are captured once per session and not overwritten, matching standard landing-page attribution behaviour
• localStorage, not sessionStorage: session boundary is the mParticle session (cleared on SESSION_END), not the browser tab — consistent with existing page view storage
• Kit-only: reads window.location.search directly; no core SDK changes required
• page_view_attributes is a new contract: backend wiring is a follow-up; extra attributes are ignored by Rokt until then

Test plan

• captureUtmParams stores present UTM keys on first call
• Only stores keys that are present (partial set)
• No-ops when URL has no UTM params
• First touch wins — does not overwrite on subsequent calls
• loadUtmParams returns null when nothing stored
• clearUtmParams removes the field without affecting other namespace fields
• Diagnostic logs emitted on capture success and write failure

[mattbodle]

assuming this is just for the initial rollout verification and then we will remove?

[alexs-mparticle]

Correct. I'll be removing these after the data has had time to soak.

[mparticle-automation]

🎉 This PR is included in version 1.35.0 🎉

The release is available on:

• v1.35.0
• GitHub release

Your semantic-release bot 📦🚀