fix(send): dismiss payment completed screen when app is backgrounded

[designsats]

Problem

When a user pays in-store and then leaves the app, the SendBitcoinCompletedScreen persists indefinitely. Returning to the app later shows a stale confirmation screen with no way to know it's from a previous session.

Closes https://github.com/blinkbitcoin/blink-wip/issues/554

Solution

Added an AppState listener inside SendBitcoinCompletedScreen that navigates the user home whenever the app transitions to the background. The screen is dismissed automatically — so when the user returns, they land on the home screen rather than a stale payment receipt.

Implementation

• send-bitcoin-completed-screen.tsx: the listener change
• Follows the same pattern as the global AppStateWrapper in app/navigation/app-state.tsx: a useRef tracks the previous app state so only the explicit active → background transition triggers the dismiss (not spurious events)
• handleNavigateHome is wrapped in useCallback to keep the effect dependency stable

Tests

Added automated coverage in __tests__/screens/send-bitcoin-completed-screen.spec.tsx:

• Navigates home (navigate("Primary")) on the active → background transition
• Does not navigate for other transitions (e.g. active → inactive, inactive → background), guarding against spurious events

Manual test plan

• Complete a payment and confirm the success screen appears
• Press home / switch apps (background the app)
• Return to Blink — verify you land on the home screen, not the payment screen
• Verify the close button on the payment screen still navigates home normally

🤖 Generated with Claude Code

[designsats]

Got this response from Claude to failing checks @grimen @blink-claw-bot
"Those branches passed before the schema drift happened. The codegen check pulls from a live schema URL — at some point after those PRs merged, the upstream schema was updated but generated.ts on main was never re-synced. Any branch created after that point will fail.

The options are:

Include generated.ts in this PR — it's technically a separate concern but it unblocks the check

Open a separate PR first that syncs generated.ts on main, then rebase ours on top of it

Leave it — the upstream maintainers may notice and fix main themselves, then our PR would pass on rebase"

[designsats]

@grimen review required

[grimen]

Add test coverage to cover the change.