fix(solana): create solana pending transactions

[taran-a]

Explanation

The snap only emitted AccountTransactionsUpdated once a transaction reached its
commitment — always terminal (confirmed/failed), never unconfirmed. The
extension's toast system needs an unconfirmed event to show "Transaction submitted"
and gates the terminal toast on it, so no toasts ever appeared for Solana
transactions (send, swap, or bridge). All sibling snaps (Bitcoin, Tron, Stellar)
already emit a pending transaction at broadcast time.

This adds TransactionMapper.createPendingTransaction and saves/emits it in
WalletService.signAndSendTransaction right after broadcasting, before arming the
SignatureMonitor (guaranteeing ordering). The confirmed transaction later upserts
over it by id. Covers all flows, since every submission path goes through this method.

Screen.Recording.2026-09-24.at.18.12.50.mov

References

• Fixes WPN-2184

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

[Battambang]

Some little code coverage to get there to pass CI: Jest: "global" coverage threshold for lines (86.88%) not met: 86.87%

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Battambang]

good one

[ulissesferreira]

Back in the day we didn't have the pending then confirmed pattern nailed down so this improvement never got added in. And since Solana transactions happened so fast we never really focused on it. But it's this kind of polish that makes things look neat ✨