feat: add swidge command to WalletConnect CLI

[arein]

Summary

• Add walletconnect swidge command for cross-chain bridging via LI.FI REST API
• Enhanced send-transaction to auto-detect insufficient ETH and offer to bridge from another chain (TTY prompt / auto in pipe mode)
• Default connect now requests all EVM chains instead of just Ethereum mainnet
• Zero new dependencies — uses fetch() for LI.FI API and RPC calls, WalletConnect for tx execution
• Library exports (index.ts, client.ts) unchanged — no breaking changes

Key design decisions

• No @lifi/sdk or viem dependency — keeps cli-sdk lightweight
• WalletConnect for execution — bridge txs go through the connected wallet (user approves in wallet app)
• ERC-20 approval uses exact amount (not max-uint256) for security
• Race-safe balance scanning — collect-then-reduce pattern for parallel RPC calls
• Input validation — CAIP-2 chain IDs and amounts validated before use

Test plan

• Build passes
• All tests pass (cli-sdk: 17 tests including 10 new swidge tests)
• Lint clean
• Manual test: walletconnect swidge with WCT->USDC cross-chain swap (approval + quote worked, user declined due to rate)
• Manual test: walletconnect connect now connects with all EVM chains
• Manual test: auto-bridge triggered via send-transaction on underfunded chain

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