fix: correct debug method availability and remove unsupported 4byteTracer

[Troublor]

Summary

• Debug methods (debug_traceTransaction, debug_traceCall, debug_traceBlockByNumber, debug_traceBlockByHash) are available on the public MegaETH RPC endpoint — not restricted to managed providers. Updated the docs to reflect this. (Resolves C-001 from auto-audits#2)
• Removed 4byteTracer from the supported tracers table — it is not handled by MegaETH's debug handler. (Resolves C-002 from auto-audits#2)
• Updated the mega-evme description to remove the outdated "no access to managed RPC" framing.

Test plan

• Verify the updated claims match live behavior at https://mainnet.megaeth.com/rpc
• Confirm 4byteTracer is indeed unsupported

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This PR was generated by an automated agent.

[claude]

Both test plan items are unchecked. The correctness of this PR's two central claims — that debug methods work on the public endpoint and that 4byteTracer is unsupported — hasn't been confirmed yet. Please verify against live behavior before merging.

[claude]

LGTM. The rate-limit claim that was flagged in the previous round has been removed.

The three factual fixes are clean:

• Debug methods now correctly documented as available on the public endpoint
• debug_traceBlockByHash added alongside debug_traceBlockByNumber
• 4byteTracer removed from the supported tracers table

The mega-evme description update is also an improvement.