feat: derived attributes display panel (Closes #11)

Add DerivedAttributesPanel showing initiative, matrix initiative,
composure, judge intent, memory, carry, run, and physical/mental/
social limits. Uses existing Attributes calculation methods. Compact
shows 2 columns, Medium 3, Expanded 5. Placed between resources and
attributes grid.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sharedUI/src/commonMain/kotlin/org/shahondin1624/App.kt

@@ -27,6 +27,7 @@ import org.jetbrains.compose.ui.tooling.preview.Preview
 import org.shahondin1624.lib.components.TestTags
 import org.shahondin1624.lib.components.UiConstants
 import org.shahondin1624.lib.components.charactermodel.CharacterHeader
+import org.shahondin1624.lib.components.charactermodel.DerivedAttributesPanel
 import org.shahondin1624.lib.components.charactermodel.ResourcePanel
 import org.shahondin1624.lib.components.charactermodel.attributespage.AttributesPage
 import org.shahondin1624.lib.components.settings.SettingsPage
@@ -311,6 +312,8 @@ private fun MainScaffold(
                         Spacer(Modifier.height(contentPadding))
                         ResourcePanel(EXAMPLE_CHARACTER.characterData, EXAMPLE_CHARACTER.attributes.edge)
                         Spacer(Modifier.height(contentPadding))
+                        DerivedAttributesPanel(EXAMPLE_CHARACTER.attributes)
+                        Spacer(Modifier.height(contentPadding))
                         AttributesPage(EXAMPLE_CHARACTER)
                     }
                 }

sharedUI/src/commonMain/kotlin/org/shahondin1624/lib/components/charactermodel/DerivedAttributesPanel.kt

@@ -0,0 +1,112 @@
+package org.shahondin1624.lib.components.charactermodel
+
+import androidx.compose.foundation.layout.*
+import androidx.compose.material3.*
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import org.shahondin1624.lib.components.TestTags
+import org.shahondin1624.lib.components.UiConstants
+import org.shahondin1624.model.attributes.Attributes
+import org.shahondin1624.theme.LocalWindowSizeClass
+import org.shahondin1624.theme.WindowSizeClass
+
+/**
+ * Displays derived attributes calculated from base attributes:
+ * initiative, matrix initiative, composure, judge intent, memory,
+ * carry, run, physical/mental/social limits.
+ */
+@Composable
+fun DerivedAttributesPanel(attributes: Attributes) {
+    val windowSizeClass = LocalWindowSizeClass.current
+    val padding = UiConstants.Spacing.medium(windowSizeClass)
+    val spacing = UiConstants.Spacing.small(windowSizeClass)
+
+    val derivedValues = listOf(
+        "Initiative" to attributes.initiative(),
+        "Matrix Init." to attributes.matrixInitiative(),
+        "Composure" to attributes.composure(),
+        "Judge Intent" to attributes.judgeIntent(),
+        "Memory" to attributes.memory(),
+        "Carry" to attributes.carry(),
+        "Run" to attributes.run(),
+        "Physical Limit" to attributes.physicalLimit(),
+        "Mental Limit" to attributes.mentalLimit(),
+        "Social Limit" to attributes.socialLimit()
+    )
+
+    Card(
+        modifier = Modifier
+            .fillMaxWidth()
+            .testTag(TestTags.PANEL_DERIVED_ATTRIBUTES)
+    ) {
+        Column(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(padding)
+        ) {
+            Text(
+                text = "Derived Attributes",
+                style = MaterialTheme.typography.titleMedium,
+                fontWeight = FontWeight.Bold,
+                modifier = Modifier.padding(bottom = spacing)
+            )
+
+            val columns = when (windowSizeClass) {
+                WindowSizeClass.Compact -> 2
+                WindowSizeClass.Medium -> 3
+                WindowSizeClass.Expanded -> 5
+            }
+
+            val rows = derivedValues.chunked(columns)
+            for (row in rows) {
+                Row(
+                    modifier = Modifier.fillMaxWidth(),
+                    horizontalArrangement = Arrangement.spacedBy(spacing)
+                ) {
+                    for (item in row) {
+                        DerivedItem(
+                            label = item.first,
+                            value = item.second,
+                            modifier = Modifier.weight(1f)
+                        )
+                    }
+                    // Fill remaining space if row is incomplete
+                    repeat(columns - row.size) {
+                        Spacer(Modifier.weight(1f))
+                    }
+                }
+                Spacer(Modifier.height(spacing))
+            }
+        }
+    }
+}
+
+@Composable
+private fun DerivedItem(label: String, value: Int, modifier: Modifier = Modifier) {
+    Surface(
+        modifier = modifier,
+        shape = MaterialTheme.shapes.small,
+        color = MaterialTheme.colorScheme.surfaceVariant
+    ) {
+        Column(
+            modifier = Modifier.padding(horizontal = 8.dp, vertical = 6.dp),
+            horizontalAlignment = Alignment.CenterHorizontally
+        ) {
+            Text(
+                text = label,
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                maxLines = 1
+            )
+            Text(
+                text = value.toString(),
+                style = MaterialTheme.typography.titleMedium,
+                fontWeight = FontWeight.Bold
+            )
+        }
+    }
+}