fix: emit presentation_id, close_reason, cache_key, build_id on paywall events

[chroxify]

Changes in this pull request

• Adds presentation_id to every paywall analytics event (paywall_open, paywall_page_view, paywall_close, etc.) — a unique ID minted once per paywall presentation, used by the dashboard to correlate a set of page views into one paywall session.
• Adds the previously-missing close_reason, cache_key, and build_id fields to the same event payload. These already exist on Paywall/PaywallInfo but were never written into PaywallInfo.eventParams().

Root cause

PaywallInfo.eventParams() on Android never included presentation_id at all — the field doesn't exist on the model, let alone get serialized. Confirmed on live ClickHouse data: presentation_id is 100% empty on Android across every SDK version, vs 0% empty on iOS. Full comparison, including exact iOS source references, in outputs/android-ios-page-tracking-comparison-2026-08-06.md from the investigation that led to this PR.

Without presentation_id, the dashboard can't group an Android paywall's page views into a single session — any Android-heavy campaign's page-view funnel silently breaks. This is what surfaced the bug: campaign 98723's page-view data looked broken.

close_reason, cache_key, build_id have the same shape of bug: the data exists on the Android models (Paywall.closeReason, .cacheKey, .buildId) but was never serialized into the outgoing event params, unlike iOS's PaywallInfo.swift.

iOS parity

• presentationId: minted as UUID().uuidString once per paywall fetch (RawPaywallResponse.swift:19), stored on Paywall, copied into PaywallInfo, emitted as "presentation_id". Android now mints it in PaywallRequestManager.updatePaywall, which — like iOS re-minting on Paywall.update(from:) — runs on every getPaywall() call that results in an actual presentation (fresh fetch, in-flight-task reuse, and Android's own paywallsByHash content-cache hit), so repeat presentations of the same cached paywall get distinct, correlatable IDs.
• close_reason: emitted as closeReason.description on both platforms now, using the same camelCase strings (systemLogic, forNextPaywall, webViewFailedToLoad, manualClose, none).
• cache_key / build_id: emitted directly, matching iOS.

Documented trade-off

PaywallLoad.Complete / PaywallProductsLoad.* events track before updatePaywall runs in the call sequence, so those response/product-loading-lifecycle events won't carry presentation_id. This is not a new inconsistency — experiment_id, variant_id, and presentation_source_type have the exact same timing gap today. The events that matter for the reported dashboard bug (paywall_open, paywall_page_view, paywall_close, and everything else tracked once a paywall is actually presented) all fire after updatePaywall and reliably get a stable, correct ID. Preload-only calls skip updatePaywall entirely via existing early-return branches, so preloading correctly doesn't mint a wasted ID.

Explicitly out of scope (flagged only, not bundled here)

• Removing the dead trigger_session_id field (// TODO remove in next major update).
• Porting state/customer_info to iOS, or intro_offer_eligibility/app_transaction_id/shimmer-load timestamps to Android.

These need a product/eng call, not a bundled change in a bug-fix PR.

Checklist

• All unit tests pass.
• All UI tests pass.
• Demo project builds and runs.
• I added/updated tests or detailed why my change isn't tested.
• I added an entry to the CHANGELOG.md for any breaking changes, enhancements, or bug fixes.
• I have run ktlint in the main directory and fixed any issues.
• I have updated the SDK documentation as well as the online docs.
• I have reviewed the contributing guide

Note on unchecked boxes: this sandbox has no JDK/Android SDK available (apt-get install openjdk-17-jdk-headless timed out), so I could not run ./gradlew test, connectedCheck, or ktlintFormat/ktlintCheck locally. All changes were reviewed manually against existing, proven patterns in the codebase (named-argument construction everywhere Paywall/PaywallInfo are built, so the new trailing fields with defaults are non-breaking; kotlinx.serialization.Transient fields are unaffected by JSON deserialization). New/updated tests are included and should be validated by CI:

• PaywallInfoTest: eventParams() includes presentation_id/close_reason/cache_key/build_id, and omits presentation_id when null.
• PaywallRequestManagerTest: getPaywall() sets a non-blank presentationId, and mints a new one on a second call that hits the request-hash cache (the direct regression test for the reported bug).
• InternalSuperwallEventTest: PaywallPageView.getSuperwallParameters() carries presentation_id sourced from paywallInfo.presentationId.

Please run CI (./gradlew test, ktlint) to confirm before merging.