test(R-I-07,R-I-08): min fundsIn amount + zero-amount guard regressions

[sh3ifu]

R-I-07 + R-I-08 — regression tests (UT-FIX-28 / UT-FIX-29)

Unit-test group for the non-zero minFundsInAmount floor added in the fix PR.

Coverage

• Config: constructor stores the value and reverts InvalidMinFundsInAmount
  on zero; setMinFundsInAmount updates + emits MinFundsInAmountUpdated,
  reverts on zero, and is onlyOwner.
• R-I-07 (zero): fundsIn(0) reverts AmountBelowMinimum; fundsOut(0)
  reverts ZeroAmount.
• R-I-08 (dust / below-min): below-floor reverts; exactly-at and above-floor
  succeed. The dust case is reproduced directly — at a 4% rule, amount 24 floors
  its commission to zero and is rejected at floor 25 (where the fee is a non-zero
  1 unit).
• Adapter overload: shares _fundsIn, so the floor applies to the
  LZ-adapter path too.