fix(exchange): round Fiat.hasDisplayableValue to currency precision

The buy-sell round-trip through the bonding curve introduces sub-quark
truncation, causing 0.01 USD to fall just below smallestUnit (9987 vs
10000 quarks). Round to the currency display digits before comparing
so the property matches formatted() semantics.

Also removes a debug println from RealVerifiedFiatCalculator.

Author: bmc08gt

services/opencode/src/main/kotlin/com/getcode/opencode/internal/exchange/RealVerifiedFiatCalculator.kt

@@ -114,7 +114,6 @@ internal class RealVerifiedFiatCalculator @Inject constructor(
         val underlyingTokenAmount = Fiat(quarks = quarks.toLong(), currencyCode = CurrencyCode.USD)
 
         val sellEstimate = Fiat.tokenBalance(quarks.toLong(), token, supply).convertingTo(rate)
-
         if (!sellEstimate.hasDisplayableValue) {
             return Result.failure(ComputeVerifiedFiatError.AmountBelowMinimum())
         }

services/opencode/src/main/kotlin/com/getcode/opencode/model/financial/Fiat.kt

@@ -163,7 +163,7 @@ data class Fiat(
 
     /** Whether this value would format as non-zero in its currency. */
     val hasDisplayableValue: Boolean
-        get() = this >= smallestUnit
+        get() = rounded(currencyCode.fractionDigits) >= smallestUnit
 
     fun valueLessThan(other: Fiat): Boolean = toDouble() < other.toDouble()
     fun valueGreaterThan(other: Fiat): Boolean = toDouble() > other.toDouble()

services/opencode/src/test/kotlin/com/getcode/opencode/internal/exchange/RealVerifiedFiatCalculatorTest.kt

@@ -420,6 +420,27 @@ class RealVerifiedFiatCalculatorTest {
         assertIs<ComputeVerifiedFiatError.AmountBelowMinimum>(result.exceptionOrNull())
     }
 
+    @Test
+    fun `one cent USD succeeds for established token`() = runTest {
+        // Regression: $0.01 USD on a high-supply (established) bonding-curve token
+        // would fail with AmountBelowMinimum due to round-trip precision loss through
+        // the bonding curve. The sell estimate quarks (e.g. 9987) fell just below the
+        // smallestUnit (10000) before rounding, even though formatted() shows "$0.01".
+        val supply = 50_000_000_000_000L // established token with high supply
+        val token = bondingCurveToken(supply = supply)
+        stubVerifiedState(CurrencyCode.USD, testMint, supply)
+
+        val result = calculator.compute(
+            amount = Fiat(fiat = 0.01, currencyCode = CurrencyCode.USD),
+            token = token,
+            rate = Rate.oneToOne,
+            trace = false,
+        )
+
+        assertTrue(result.isSuccess, "Expected success but got: ${result.exceptionOrNull()}")
+        assertTrue(result.getOrThrow().localFiat.underlyingTokenAmount.quarks > 0)
+    }
+
     // endregion
 
     // region helpers