fix / remove double-counting of priority fee in getFee

[fengtality]

Summary

• Fix transaction fee calculation that was double-counting priority fees
• Solana RPC meta.fee already includes both base fee and priority fee
• Previous code extracted priority fee from compute budget instructions and added it again

New in this update:

• Add Solana error parser for user-friendly error messages
• Simplify /poll endpoint (remove tokens/walletAddress params)
• Parse on-chain transaction errors into structured format: TYPE (code): message
• Add error helper functions for consistent error handling

Error Parser

Parses program-specific error codes into user-friendly messages:

Program	Error Codes	Type
Jupiter	6001	SLIPPAGE_EXCEEDED
Meteora DLMM	6004, 6018, 6040	SLIPPAGE_EXCEEDED, MATH_OVERFLOW, INVALID_POSITION
Raydium CLMM	6029-6031, 6037	SLIPPAGE_EXCEEDED, PRICE_LIMIT_OVERFLOW
Orca Whirlpool	6029-6031	SLIPPAGE_EXCEEDED

Example poll response for failed transaction:

{
  "txStatus": -1,
  "fee": 0.000403,
  "error": "SLIPPAGE_EXCEEDED (0x1771): Slippage tolerance exceeded. The output amount would be less than your minimum.",
  "txData": {...}
}

Affected Connectors

Connector	Status
Meteora CLMM	✅ Fixed
Orca CLMM	✅ Fixed
Raydium CLMM	✅ Unaffected (reads meta.fee directly)
PancakeSwap-Sol CLMM	✅ Unaffected (reads meta.fee directly)

Related PRs

QA Note: These 4 PRs should be tested together as a coordinated release.

Repo	PR	Description
hummingbot	#8150	Move retry logic from executors to connectors
hummingbot-api	#142	Add SwapExecutor with connector-level retry
hummingbot-api-client	#16	Add swap/lp executor client support
gateway	#620	Fix fee calculation, add error parsing (this PR)

Test plan

• Verify build passes
• Test LP operations on Meteora and verify fee is correct
• Compare reported fee with Solscan transaction fee
• Test poll endpoint with failed transaction signature
• Verify error parsing for slippage errors

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