feat: connection issues view

[jvsena42]

Related to #873

Description

This PR adds a reusable connection issues overlay view and improves network recovery behavior across multiple flows.

Connection Issues Overlay

• Adds ConnectionIssuesView composable with phone illustration, dashed gradient rings, and a loading spinner
• Integrates the overlay into SendSheet, ReceiveSheet, ForceTransferSheet, SpendingAmountScreen, SpendingConfirmScreen, and SavingsConfirmScreen using AnimatedVisibility
• Auto-dismisses when connectivity is restored, preserving the underlying flow state

Network Recovery Improvements

• LightningRepo.canSend() fallback: When channels are loading (node Starting or channels not yet usable after reconnect), falls back to cached totalLightningSats balance instead of returning false — fixes unified invoices only showing savings option after reconnecting
• SpendingAmountScreen refresh: Re-triggers updateLimits() when connectivity state changes, so the "Available" field updates after coming back online
• IsOnlineTracker fix: Fixed isFirstEmission flag never being set to false, which prevented connectivity toasts from ever appearing
• LightningRepo.awaitPeerConnected(): New method that polls for peer reconnection (up to 30s) before attempting cooperative channel close — prevents "Cannot begin shutdown while peer is disconnected" errors during transfer to savings after internet toggle
• TransferViewModel.closeChannels(): Calls awaitPeerConnected() before attempting cooperative close, reducing unnecessary INTERRUPTED state in the savings progress screen

Preview

transfer-to-spending.webm

receive-sheet.webm

send-sheet.webm

transfer-to-savings.webm

QA Notes

Connection Issues Overlay

1. Open the Send Bitcoin sheet, toggle airplane mode on
   • Connection Issues overlay should fade in over the send flow
   • Title should read "Send Bitcoin"
   • Dashed yellow rings and phone illustration should be visible
   • Spinner should be animating at the bottom
2. Re-enable connectivity
   • Overlay should fade out
   • Send flow state should be preserved (no navigation reset)
3. Repeat for Receive Bitcoin sheet (title: "Receive Bitcoin")
4. Repeat for Force Transfer sheet (title: "Transfer Funds")
5. Repeat for Transfer to Spending screens (amount + confirm)
6. Repeat for Transfer to Savings confirm screen
7. Verify the overlay does not appear when connectivity is stable

Network Recovery — Send Flow

8. With on-chain + lightning balance, enable airplane mode → open send sheet → disable airplane mode → paste unified zero-amount invoice
   • Both savings AND spending options should appear (not just savings)

Network Recovery — Transfer to Savings

9. Toggle airplane mode off/on → immediately confirm transfer to savings
   • Progress screen should wait for peer reconnection and show SUCCESS (not INTERRUPTED)
   • Check logs for "Waiting for peer to reconnect" message

Connectivity Toasts

10. Toggle airplane mode on → "Internet Connectivity Issues" warning toast should appear
11. Toggle airplane mode off → "Internet Connection Restored" success toast should appear

[jvsena42]

@piotr-iohk I suppose there is a missing update in a test flow, because of the detail button