fix: reject EVM txs below base fee at mempool

[mmsqe]

Description

to avoid underpriced evm tx pass pool's default 0 min-tip gate, silently queued but never included

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Author Checklist

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I have...

• tackled an existing issue or discussed with a team member
• left instructions on how to review the changes
• targeted the main branch

[greptile-apps]

PR author is not in the allowed authors list.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.95%. Comparing base (a739fe1) to head (20a7395).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1223      +/-   ##
==========================================
- Coverage   66.99%   66.95%   -0.04%     
==========================================
  Files         320      320              
  Lines       23436    23441       +5     
==========================================
- Hits        15702    15696       -6     
- Misses       6576     6583       +7     
- Partials     1158     1162       +4     

Files with missing lines	Coverage Δ
mempool/mempool.go	81.90% <100.00%> (+0.29%)	⬆️

... and 3 files with indirect coverage changes

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