feat(cli): add tx simulate and trace subcommands

[ByteYue]

Summary

Three new read-only helpers that wrap reth's debug RPC for the common "what would happen / what happened" developer questions:

• tx simulate --from --to --data [--value] [--block] — runs eth_call + eth_estimateGas and pretty-prints the outcome. Reverts are decoded for the two standard ABI signatures (Error(string), Panic(uint256)); unknown selectors fall back to raw hex. Exit code is non-zero on revert so simulate can gate scripts.

• tx trace <hash> [--tracer call|prestate|4byte|opcode|noop] — wraps debug_traceTransaction. The call tracer is rendered as an indented tree (• CALL 0xfrom → 0xto value=N gas=used/limit); everything else prints pretty JSON.

• tx trace-call --from --to --data [--value] [--block] [--tracer ...] — wraps debug_traceCall for hypothetical calls, using the same tracers and rendering.

--output json on any of the three produces machine-readable output for scripting.

Design notes

• No node-side changes — everything layers on reth methods already exposed (eth_call, eth_estimateGas, debug_traceTransaction, debug_traceCall).
• Revert decoding lives in tx/common.rs with unit tests for the standard selectors, the empty-data case, and the hex-fallback case. Custom-error ABI support is deferred.
• Relationship with foundry's cast: cast covers vanilla EVM flows; this PR focuses on gravity-specific simulation flow + making revert output first-class. No overlap we're duplicating.

Test plan

• Unit tests (revert decoding Error/Panic/empty/unknown, hex parsing) — 6 tests pass
• tx simulate successful EOA transfer against localnet → prints success / return / gas
• tx simulate with insufficient balance → reverted, exit 1
• tx trace <real tx hash> (callTracer) → tree output with from/to/value/gas
• tx trace --tracer prestate → pretty JSON passthrough
• tx trace-call → successfully traces hypothetical call
• --output json produces structured output for simulate and trace
• Invalid tx hash → clear error, exit 1
• Missing --rpc-url → clear error with init hint