Hide the "Not priced by Manual" label for Manual

Manual's default-currency field being unpriced just means no rate has
been typed in yet, not an actual pricing error, so the label (and the
red error styling that came with it) no longer applies when it's the
active source.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FXcrACM5sok3M1KQJ8kByy

shared/src/commonMain/kotlin/xyz/tyiu/satsprice/ui/PriceScreen.kt

@@ -350,8 +350,8 @@ fun PriceScreen(
                                     keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Decimal),
                                     singleLine = true,
                                     enabled = isPriced,
-                                    isError = !isPriced,
-                                    supportingText = if (isPriced) {
+                                    isError = !isPriced && !state.isManualSource,
+                                    supportingText = if (isPriced || state.isManualSource) {
                                         null
                                     } else {
                                         { Text(stringResource(MR.strings.currency_not_priced, state.sourceName)) }