feat(eightsaf-extension): add EightSaf wallet adapter for Interchain Kit

[Mechack08]

Summary

• Add @interchain-kit/eightsaf-extension for EightSaf browser extension support
• Wire window.eightsaf through ExtensionWallet and CosmosWallet
• Enable Safrochain dApp flows: connect, sign, send, delegate, and broadcast
• Register Chrome and Firefox store download links in wallet metadata
• Add package README with chain-registry usage and Safrochain setup notes

Changes

• New package: wallets/eightsaf-extension
• Workspace lockfile updated for the new package

Test plan

• pnpm --filter @interchain-kit/core build
• pnpm --filter @interchain-kit/eightsaf-extension test
• pnpm --filter @interchain-kit/eightsaf-extension build
• Install EightSaf extension (Chrome or Firefox)
• In a Safrochain dApp, add eightsafWallet to ChainProvider
• Verify connect works for the active network (safrochain-1 or safrochain-testnet-1)
• Verify sign and broadcast (send / delegate) through EightSaf approval popups

Notes

• EightSaf is extension-only for now (no mobile WalletConnect adapter)
• dApp chain config must match the network selected in the EightSaf extension
• Safrochain mainnet is available in chain-registry: https://github.com/hyperweb-io/chain-registry/blob/main/v2/packages/chain-registry/src/mainnet/safrochain/chain.ts