fix(kmp): replace remaining jvm-only encoding calls in common sources

The previous round fixed the convention plugin and the native expect
declarations, which let both platforms compile far enough to reveal the
next layer: a handful of jvm-only call forms that survived the original
kotlin/native sweep because they look like plain kotlin.

String.toByteArray() and Charsets.UTF_8 live in java.nio.charset and do
not exist on kotlin/native; the stdlib equivalents encodeToByteArray()
compile everywhere and are byte-identical for utf-8, so the APRS packet
length budget and the ADIF field length calculation keep their exact
arithmetic. The DatabaseRepoTest helpers kept an InputStream return type
after their bodies were moved to ByteArray sources, and the java.io
import was gone with the sweep, so the android unit test task could not
resolve them; the fake source maps were already typed () -> ByteArray,
so the return type simply follows the data it now feeds.

core/data/src/test/java/com/rtbishop/look4sat/core/data/repository/DatabaseRepoTest.kt

@@ -194,12 +194,12 @@ class DatabaseRepoTest {
         assertTrue("no entries may be inserted", localSource.insertedEntries.isEmpty())
     }
 
-    private fun validCsvBytes(): InputStream = """
+    private fun validCsvBytes(): ByteArray = """
         OBJECT_NAME,OBJECT_ID,EPOCH,MEAN_MOTION,ECCENTRICITY,INCLINATION,RA_OF_ASC_NODE,ARG_OF_PERICENTER,MEAN_ANOMALY,EPHEMERIS_TYPE,CLASSIFICATION_TYPE,NORAD_CAT_ID,ELEMENT_SET_NO,REV_AT_EPOCH,BSTAR,MEAN_MOTION_DOT,MEAN_MOTION_DDOT
         ISS (ZARYA),1998-067A,2021-11-16T12:28:09.322176,15.48582035,.0004694,51.6447,309.4881,203.6966,299.8876,0,U,25544,999,31220,.31985E-4,.1288E-4,0
     """.trimIndent().encodeToByteArray()
 
-    private fun validTleBytes(): InputStream = """
+    private fun validTleBytes(): ByteArray = """
         ISS (ZARYA)
         1 25544U 98067A   21320.51955234  .00001288  00000+0  31985-4 0  9990
         2 25544  51.6447 309.4881 0004694 203.6966 299.8876 15.48582035312205

core/domain/src/commonMain/kotlin/com/rtbishop/look4sat/core/domain/aprs/AprsBeacon.kt

@@ -91,7 +91,7 @@ object AprsBeacon {
         )
         val header = "$source>$DESTINATION,$PATH:="
         val body = position.toUncompressedString()
-        val room = MAX_LINE_BYTES - CRLF_BYTES - header.toByteArray().size - body.toByteArray().size
+        val room = MAX_LINE_BYTES - CRLF_BYTES - header.encodeToByteArray().size - body.encodeToByteArray().size
         return Result.Line(header + body + sanitiseComment(comment, room))
     }
 

core/domain/src/commonMain/kotlin/com/rtbishop/look4sat/core/domain/wavelog/WaveLogApi.kt

@@ -312,7 +312,7 @@ object WaveLogApi {
     /** v1 ADIF string (freq in MHz, length = UTF-8 byte count, sat_name normalized) */
     internal fun toAdif(qso: WavelogQso, gridsquare: String, satName: String): String {
         fun field(name: String, value: String): String {
-            val bytes = value.toByteArray(Charsets.UTF_8).size
+            val bytes = value.encodeToByteArray().size
             return "<$name:$bytes>$value"
         }
         val satMode = satModeFrom(qso.freqTxHz, qso.freqRxHz)