feat: dynamic gas margin for Tempo recovery based on user gas params

[bhavesh-prasad]

Summary

Implements the full TSS recovery flow for the Tempo chain (TIP-20 / EIP-7702).

What was there before

• buildUnsignedSweepTxnTSS and recoveryBlockchainExplorerQuery were stubs returning empty/dummy objects
• No signed recovery path existed

What this PR adds

Recovery infrastructure (tempo.ts)

• recoveryBlockchainExplorerQuery — routes Etherscan-style queries to Tempo's Alchemy JSON-RPC endpoint (configured via environments.ts)
• queryTempoRpc — translates account/balance, account/tokenbalance, and account/txlist queries into eth_call / eth_getTransactionCount JSON-RPC calls
• buildTempoSweepTx — shared helper that queries token balance, computes sweep amount, and builds an unsigned TIP-20 transfer transaction; used by both recovery paths
• recoverTSS — overrides base-class recovery with two paths:
  • Unsigned sweep (plain public key shares): delegates to buildUnsignedSweepTxnTSS
  • Signed sweep (encrypted keys + passphrase): builds a TIP-20 tx, hashes it, signs via MPC v2 ECDSA, attaches the signature, and returns the broadcast-ready hex
• buildUnsignedSweepTxnTSS — builds an unsigned TIP-20 sweep and returns the UnsignedSweepTxMPCv2 structure for offline vault signing

Dynamic gas margin

• Removes hardcoded GAS_MARGIN_UNITS = 20_000n constant
• Gas margin is now computed from user-supplied params: gasMarginUnits = gasLimit × maxFeePerGas / 10^12
• Matches the gasLimit × gasPrice pattern used across all ETH-like coin recovery flows in abstract-eth; the /10^12 factor converts from wei scale (18 decimals) to pathUSD's TIP-20 units (6 decimals)

Environment config (environments.ts)

• Adds Tempo evm config entry so recoveryBlockchainExplorerQuery can resolve the RPC URL and API token

[linear-code]

CECHO-917