Fix SubscriptionsWebViewActivity.canGoBack UnsupportedOperationException

[joshliebe]

Task/Issue URL: https://app.asana.com/1/137249556945/project/1200204095367872/task/1213736584422131?focus=true

Description

• Returns early if the URL is non-hierarchical on the subscriptions WebView (allowing the back nav)

Steps to test this PR

• Go to the subscriptions WebView
• Verify that you can go back

---

Note

Low Risk
Low risk, localized change to back-navigation gating that adds a safety check to prevent an UnsupportedOperationException when the WebView URL is non-hierarchical.

Overview
Fixes a crash in SubscriptionsWebViewActivity.canGoBack() by checking uri.isHierarchical before reading query parameters.

Non-hierarchical URLs now bypass the preventBackNavigation query check, preventing UnsupportedOperationException during back navigation decisions.

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[joshliebe]

• Fix SubscriptionsWebViewActivity.canGoBack UnsupportedOperationException #8027 👈 (View in Graphite)
• develop

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