Add origin when launching paywall

[nalcalag]

Task/Issue URL: https://app.asana.com/1/137249556945/project/1207260194172075/task/1218019265846236?focus=true
Tech Design URL (if applicable):
API Proposals URL(s) (if applicable):

Description

Attach origin to the URL when SubscriptionsWebViewActivity is launched with an origin param but the URL itself doesn't already contain it

Steps to test this PR

Pre steps

• Apply patch on https://app.asana.com/1/137249556945/project/1209991789468715/task/1210448620621729?focus=true

App Settings

• Install from branch
• Go to Settings
• Tap on Subscribe to DuckDuckGo
• Check in logcat that the paywall is launched with origin=funnel_appmenu_android appended to the URL

No UI changes

---

Note

Low Risk
Scoped to subscription WebView URL construction and pixel param key naming; origin values remain allowlist-gated with no change to purchase or auth flows.

Overview
Ensures the subscription paywall WebView loads with a funnel origin query param when launch params carry an allowlisted origin but the target URL does not already include it—so the web offer page can attribute the entry point consistently with native telemetry.

Adds String.appendFunnelOriginParam, which only appends origin for values in FUNNEL_ORIGIN_ALLOWLIST, skips non-hierarchical URLs and URLs that already have origin, and is applied on every SubscriptionsWebViewActivity param resolution path (purchase, upgrade, and default). Introduces ORIGIN_QUERY_PARAM_KEY and replaces hardcoded "origin" strings in RealSubscriptions and SubscriptionPixelSender; unit tests cover the URL helper.

^{Reviewed by Cursor Bugbot for commit 91b14ce. Bugbot is set up for automated code reviews on this repo. Configure here.}

[nalcalag]

• Add origin when launching paywall #9750 👈 (View in Graphite)
• develop

This stack of pull requests is managed by Graphite. Learn more about stacking.