feat: color system name in home screen title using system color

Adds toThemeAdapted() utility that clamps HSV brightness for legibility
(≤0.55 in light theme, ≥0.75 in dark theme). Only the system name is
colored; "Welcome, " retains the default top bar text color.

Author: fullynocturnal

sheaf/app/src/main/java/systems/lupine/sheaf/ui/components/Components.kt

@@ -18,6 +18,7 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Warning
 import androidx.compose.material3.*
 import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
+import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -116,6 +117,17 @@ fun parseColor(hex: String): Color? = runCatching {
     Color(android.graphics.Color.parseColor(hex))
 }.getOrNull()
 
+// Adjusts a color's HSV brightness so it stays legible on the current theme background:
+// darkened to ≤0.55 in light theme, brightened to ≥0.75 in dark theme.
+@Composable
+fun Color.toThemeAdapted(): Color {
+    val dark = isSystemInDarkTheme()
+    val hsv = FloatArray(3)
+    android.graphics.Color.colorToHSV(this.toArgb(), hsv)
+    hsv[2] = if (dark) hsv[2].coerceAtLeast(0.75f) else hsv[2].coerceAtMost(0.55f)
+    return Color(android.graphics.Color.HSVToColor(hsv))
+}
+
 // ── Member card ───────────────────────────────────────────────────────────────
 
 @OptIn(ExperimentalFoundationApi::class)

sheaf/app/src/main/java/systems/lupine/sheaf/ui/home/HomeScreen.kt

@@ -15,7 +15,10 @@ import androidx.compose.material3.pulltorefresh.PullToRefreshBox
 import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.SpanStyle
+import androidx.compose.ui.text.buildAnnotatedString
 import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.text.withStyle
 import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.Lifecycle
@@ -55,7 +58,20 @@ fun HomeScreen(
         contentWindowInsets = WindowInsets(0),
         topBar = {
             SheafCenterAlignedTopAppBar(
-                title = { Text(state.system?.name?.let { "Welcome, $it" } ?: "Welcome") },
+                title = {
+                    val systemColor = state.system?.color?.let { parseColor(it)?.toThemeAdapted() }
+                    Text(
+                        text = buildAnnotatedString {
+                            append("Welcome")
+                            state.system?.name?.let { name ->
+                                append(", ")
+                                withStyle(SpanStyle(color = systemColor ?: LocalContentColor.current)) {
+                                    append(name)
+                                }
+                            }
+                        },
+                    )
+                },
             )
         },
         floatingActionButton = {