Subscriptions: Improve Back button experience

[nalcalag]

Task/Issue URL: https://app.asana.com/1/137249556945/project/1204912272578138/task/1215248979171838?focus=true

Description

Improve back behaviour in subscription screen

Steps to test this PR

Pre steps

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

No purchase

• Instal from branch
• Go to Settings > Onboarding Dev Settings
• Toggle off DAX_INTRO_PRIVACY_PRO
• Go back to browser where subscription dialog will appear
• Tap on 'Learn More'
• Exit subscription screen without finishing a purchase
• Verify it gets back to the browser and no settings screen

purchase success

• Go to Settings > Onboarding Dev Settings
• Toggle off DAX_INTRO_PRIVACY_PRO
• Go back to browser where subscription dialog will appear
• Tap on 'Learn More'
• Purchase a test subscription
• Verify it now gets back to the settings screen

restore success

• Remove account from device
• Tap on 'I have a Subscription'
• Tap on 'Add via Google Play Account'
• Verify it now gets back to the settings screen

No UI changes

---

Note

Low Risk
Navigation-only changes in the subscriptions UI with no billing, auth, or data-handling logic modified; main risk is incorrect back-stack behavior in edge entry points.

Overview
Subscription launch no longer pre-stacks Settings under the subscription web view. launchSubscription starts only SubscriptionsWebViewActivity, so dismissing without completing a purchase returns the user to the prior screen (e.g. browser) instead of Settings.

Completion paths route to Settings when appropriate. backToSettings is renamed to finishToSettings: for non-activate flows it starts Settings with CLEAR_TOP / SINGLE_TOP then finishes; activate URL still sets RESULT_OK only. Purchase success, recovered, and JS BackToSettings commands use this helper instead of a bare finish().

Hardware/toolbar back after a completed purchase flow (success, waiting, or recovered) calls finishToSettings() when the WebView cannot go back, aligning back with post-purchase expectations. Unit tests for launchSubscription now expect a single startIntent (web view only).

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[nalcalag]

• Subscriptions: Improve Back button experience #8923 👈 (View in Graphite)
• develop

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