feat(ui): OnboardingView 첫 화면에 앱 버전 표시 (demo flavor "2.0.0-demo")

사용자 요청 (2026-08-11): 맨 첫 화면 (Onboarding) 에도 버전 노출.
기존엔 HomeView 에만 있음 · 첫 화면 진입 시 확인 어려움.

변경:
  · OnboardingView subtitle 아래에 versionName (12sp · secondary text)
  · packageManager.getPackageInfo().versionName 사용 → demo flavor 는
    자동으로 "-demo" 접미사 반영 → "2.0.0-demo" 표시.
  · runCatching · 실패 시 빈 문자열 (필수기능 영향 없음).

app/src/main/java/com/medithings/vesiscan/ui/views/onboarding/OnboardingView.kt

@@ -7,10 +7,12 @@ import androidx.compose.material3.Button
 import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Brush
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextAlign
@@ -23,6 +25,11 @@ import com.medithings.vesiscan.ui.theme.*
 
 @Composable
 fun OnboardingView(appState: AppState) {
+    val context = LocalContext.current
+    val versionName = remember(context) {
+        runCatching { context.packageManager.getPackageInfo(context.packageName, 0).versionName }
+            .getOrNull() ?: ""
+    }
     Column(
         modifier = Modifier
             .fillMaxSize()
@@ -51,6 +58,16 @@ fun OnboardingView(appState: AppState) {
             textAlign = TextAlign.Center
         )
 
+        Spacer(modifier = Modifier.height(8.dp))
+
+        // 2026-08-11: 첫 화면에도 앱 버전 표시. demo flavor 는 자동으로 "-demo" 접미사.
+        Text(
+            text = versionName,
+            fontSize = 12.sp,
+            color = MlSecondaryText.copy(alpha = 0.6f),
+            textAlign = TextAlign.Center,
+        )
+
         Spacer(modifier = Modifier.weight(2f))
 
         Button(