feat: add Solana Wallet Standard support

Integrate Solana via Wallet Standard protocol — no window.solana
(avoids Phantom conflicts). Signs transactions through vault v11
REST API and broadcasts client-side via Solana JSON-RPC.

New files:
- solanaHandler.ts: background handler matching vault v11 endpoints
- solana-wallet-standard.ts: KeepKeySolanaWallet class (5 features)
- solana-wallet-register.ts: wallet-standard event registration

Modified:
- injected.ts: register Solana wallet, bump version, 5min timeout
- methods.ts: route 'solana' chain to handler
- types.ts: add 'solana' to ChainType union
- content/index.ts: 5min timeout for hardware signing
- Transaction.tsx: handle 'solana' chain type

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: BitHighlander

chrome-extension/package.json

@@ -23,7 +23,11 @@
     "ethers": "^6.13.2",
     "keepkey-vault-sdk": "^2.0.1",
     "uuid": "^10.0.0",
-    "webextension-polyfill": "^0.12.0"
+    "webextension-polyfill": "^0.12.0",
+    "@wallet-standard/wallet": "^1.1.0",
+    "@wallet-standard/base": "^1.1.0",
+    "@wallet-standard/features": "^1.1.0",
+    "@solana/wallet-standard-features": "^1.3.0"
   },
   "devDependencies": {
     "@extension/dev-utils": "workspace:*",