feat(update): notify about app updates on launch (chat banner) (#891)

Fires one silent update check per installed version at app start
(UpdateNoticeManager, release builds only) and shows a non-blocking
banner on the chat screen when a newer release exists. The About tab
adopts the launch result instead of re-pinging GitHub; dismissals
return on the next launch via the persisted latest tag.

Closes #890

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/ui/common/UpdateNoticeBanner.kt

@@ -0,0 +1,64 @@
+package com.m57.hermescontrol.ui.common
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Update
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import com.m57.hermescontrol.R
+
+/**
+ * Chat-screen banner for the launch update check (issue #890): a newer
+ * Hermes Mobile release exists. "Update" jumps into the About-tab install
+ * flow; "Later" dismisses for the session (the banner returns next launch).
+ */
+@Composable
+fun UpdateNoticeBanner(
+    latestTag: String,
+    onUpdate: () -> Unit,
+    onDismiss: () -> Unit,
+) {
+    Row(
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 12.dp, vertical = 6.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        Icon(
+            imageVector = Icons.Filled.Update,
+            contentDescription = null,
+            tint = MaterialTheme.colorScheme.primary,
+            modifier = Modifier.padding(top = 2.dp),
+        )
+        Text(
+            text = stringResource(R.string.update_notice_banner_text, latestTag),
+            style = MaterialTheme.typography.bodySmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.weight(1f),
+        )
+        TextButton(onClick = onUpdate) {
+            Text(
+                text = stringResource(R.string.update_notice_banner_action),
+                style = MaterialTheme.typography.labelSmall,
+            )
+        }
+        TextButton(onClick = onDismiss) {
+            Text(
+                text = stringResource(R.string.action_dismiss),
+                style = MaterialTheme.typography.labelSmall,
+            )
+        }
+    }
+}