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/data/remote/HermesApiService.kt

@@ -128,6 +128,7 @@ import com.m57.hermescontrol.data.model.UpdateProfileDescriptionRequest
 import com.m57.hermescontrol.data.model.UpdateProfileModelRequest
 import com.m57.hermescontrol.data.model.UpdateProfileSoulRequest
 import com.m57.hermescontrol.data.model.UpdateRawConfigRequest
+import com.m57.hermescontrol.data.model.UpdateReceiptResponse
 import com.m57.hermescontrol.data.model.WebhookSubscription
 import com.m57.hermescontrol.data.model.WebhookToggleSubscriptionRequest
 import com.m57.hermescontrol.data.model.WebhooksResponse
@@ -800,6 +801,12 @@ interface HermesApiService {
     @POST("api/hermes/update")
     suspend fun updateHermes(): Response<ActionResponse>
 
+    // ── Admin: Hermes update receipt (issue #958) ──
+    // Returns the durable record of the last `hermes update` run. 404 when no
+    // receipt exists yet (handled as "no info to show", not an error).
+    @GET("api/hermes/update/receipt")
+    suspend fun getUpdateReceipt(): Response<UpdateReceiptResponse>
+
     // ── Admin: Portal ─────────────────────────────────────────────────
     @GET("api/portal")
     suspend fun getPortal(): Response<PortalResponse>