feat(update): surface backend update receipt in action popup (#958) (#964)

Adopt GET /api/hermes/update/receipt and append its summary to the
end of the hermes-update action progress popup after it finishes.
Additive only: existing checkHermesUpdate + connection-retry polling
is untouched. 404 (old backend) is handled gracefully.

- add UpdateReceiptResponse data model matching backend schema
- add getUpdateReceipt() to HermesApiService
- ActionProgressController gains trailingLines + pushTrailingLines
- ActionProgressDialog renders trailingLines after the log
- SystemViewModel fetches receipt on action finish and formats it
- extract pure formatUpdateReceiptLines for mockk-free testing

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

@@ -40,6 +40,11 @@ data class ActionProgressState(
     val lines: List<String> = emptyList(),
     val exitCode: Int? = null,
     val error: String? = null,
+    /**
+     * Host-appended lines shown after the log tail once the action finishes
+     * (e.g. a structured update receipt). Empty unless the host pushes them.
+     */
+    val trailingLines: List<String> = emptyList(),
 )
 
 /**
@@ -150,6 +155,16 @@ class ActionProgressController(
         _state.update { it.copy(phase = ActionProgressPhase.FAILED, error = error) }
     }
 
+    /**
+     * Append host-supplied lines after the log tail (e.g. an update receipt
+     * summary). Safe to call after the action has finished; only affects
+     * [ActionProgressState.trailingLines], never the poll loop.
+     */
+    fun pushTrailingLines(lines: List<String>) {
+        if (lines.isEmpty()) return
+        _state.update { it.copy(trailingLines = it.trailingLines + lines) }
+    }
+
     /** Stop tracking and hide the dialog. Safe mid-run (action keeps going). */
     fun dismiss() {
         pollJob?.cancel()

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

@@ -16,6 +16,7 @@ import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
@@ -169,6 +170,26 @@ fun ActionProgressDialog(
                         color = statusColors.error,
                     )
                 }
+
+                // Host-appended trailing block (e.g. update receipt summary),
+                // shown after the log tail once the action has finished.
+                if (state.trailingLines.isNotEmpty()) {
+                    HorizontalDivider(
+                        modifier = Modifier.padding(vertical = spacing.sm),
+                        color = MaterialTheme.colorScheme.outlineVariant,
+                    )
+                    Column(
+                        verticalArrangement = Arrangement.spacedBy(2.dp),
+                    ) {
+                        state.trailingLines.forEach { line ->
+                            Text(
+                                text = line,
+                                style = MaterialTheme.typography.bodySmall,
+                                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                            )
+                        }
+                    }
+                }
             }
         },
         confirmButton = {