Add TRON vault swap for Chainflip

[0xh3rman]

Context

Chainflip has added Tron support (native TRX and USDT-TRC20 as source assets), currently live on the Perseverance testnet. Add Tron as a Chainflip swap source in the swap provider layer.

Key difference from EVM

Tron vault swaps are not a Vault contract call (no xSwapNative / xSwapToken). Instead:

• Direct transfer of TRX/USDT to the Chainflip Vault address.
• Encoded swap parameters attached as the transaction note (the data / memo field).
• No TRC-20 approval needed — it's a transfer, not transferFrom.
• Cheaper: no protocol fetch tx, so no ingress fee. Recommended swap method on Tron.

Conceptually closer to the Bitcoin deposit-with-data model than the EVM contract-call model.

Flow

1. Request encoding via broker_request_swap_parameter_encoding with "chain": "Tron" in both source_asset and extra_parameters; refund address must be a valid Tron address.
2. Response: { chain, calldata, value, to, note, source_token_address? }.
3. Build tx → attach note to the data field → sign → broadcast.

Tasks

• Add Tron as a Chainflip source asset (TRX + USDT-TRC20) in provider config
• Wire broker_request_swap_parameter_encoding request for chain: Tron
• Parse response fields (value, to, note, calldata, source_token_address)
• TRX path: build TransferContract to Vault, value in sun, set note as tx data
• USDT-TRC20 path: build TriggerSmartContract → transfer(address,uint256) to Vault, set note as tx data (no approval step)
• Handle Tron address encoding (base58 T… ↔ 21-byte 0x41… hex) — RPC returns to in hex
• Encode broker commission + affiliates (g1) via broker_commission in the request → lands in note cfParameters
• Reuse existing Tron tx-building / signing in the Rust core
• Test on Perseverance with the testnet Vault address; verify the swap is witnessed and egresses

⚠️ Do not hand-roll

Don't hand-encode the note / cfParameters — incorrectly encoded params can lose funds. Always use the broker RPC to produce it.

Links

• Tron vault swaps: https://docs.chainflip.io/brokers/vault-swaps-api/tron
• Vault swaps overview: https://docs.chainflip.io/brokers/broker-vault-swaps
• EVM vault swaps (for contrast): https://docs.chainflip.io/brokers/vault-swaps-api/evm
• Encoding reference (cfParameters): https://docs.chainflip.io/brokers/vault-swaps-api/encoding-reference
• Testnet addresses: https://docs.chainflip.io/protocol/supported-chains-assets/testnet-addresses
• Mainnet addresses: https://docs.chainflip.io/protocol/supported-chains-assets/mainnet-addresses
• Announcement: https://blog.chainflip.io/chainflip-adds-tron-native-swaps/