feat: add Solana Wallet Standard support

[BitHighlander]

Summary

• Adds Solana chain support via Wallet Standard protocol (no window.solana — avoids Phantom conflicts)
• Signs transactions through vault v11 REST API (POST /solana/sign-transaction)
• Broadcasts client-side via Solana JSON-RPC (vault has no broadcast endpoint)
• Increases content script timeout to 5 minutes for hardware wallet signing

New Files

File	Purpose
solanaHandler.ts	Background chain handler — vault v11 sign + client-side broadcast
solana-wallet-standard.ts	KeepKeySolanaWallet class with 5 standard features
solana-wallet-register.ts	Event-based wallet registration (callback pattern)

Modified Files

File	Change
injected.ts	Import + register Solana wallet, version 2.1.0, 5min timeout
methods.ts	Route solana chain to handleSolanaRequest
types.ts	Add 'solana' to ChainType union
content/index.ts	Timeout 30s → 300s for hardware signing
Transaction.tsx	Handle 'solana' as 'other' transaction type
package.json	Add @wallet-standard/* and @solana/wallet-standard-features deps

Architecture

dApp → wallet-standard:register-wallet event
     → KeepKeySolanaWallet (injected.ts)
     → content script relay
     → background solanaHandler
     → vault v11: POST /solana/sign-transaction { raw_tx: base64 }
     → client-side broadcast via Solana JSON-RPC

Key Design Decisions

1. Wallet Standard only — never mounts window.solana (conflicts with Phantom)
2. accounts is a getter — required by StandardWalletAdapter (arraysEqual2 crashes on undefined)
3. Event detail is a callback — ({register}) => register(wallet), not an object
4. No sign-message endpoint — reuses /solana/sign-transaction with raw message bytes
5. Client-side broadcast — vault v11 has no broadcast endpoint; sends directly to api.mainnet-beta.solana.com
6. Inline base58 — no external dependency for address decoding

Test plan

• Load extension in Chrome, verify KeepKey appears in Solana dApp wallet picker
• Connect to a Solana dApp (e.g., Jupiter, Raydium) — should return device address
• Sign a transaction — vault should prompt on device, return signed tx
• Sign and send — should broadcast via Solana RPC and return tx signature
• Verify Ethereum/EVM functionality is unaffected
• Verify no window.solana in browser console

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