fix(#201): fix platforms endpoint response shape mismatch

GET /api/messaging/platforms returns a JSON object with a platforms
array inside, but the app expected a bare array. Wraps the response
in a new MessagingPlatformResponse model.

- Adds MessagingPlatformResponse.kt wrapper model
- Updates HermesApiService.kt return type + adds profile query param
- Updates ChannelsViewModel.kt to unwrap .platforms
- Updates E2eIntegrationTest.kt mock to match new response shape

app/src/test/java/com/m57/hermescontrol/E2eIntegrationTest.kt

@@ -14,6 +14,7 @@ import com.m57.hermescontrol.data.model.KanbanColumn
 import com.m57.hermescontrol.data.model.KanbanTask
 import com.m57.hermescontrol.data.model.LogResponse
 import com.m57.hermescontrol.data.model.MessagingPlatform
+import com.m57.hermescontrol.data.model.MessagingPlatformResponse
 import com.m57.hermescontrol.data.model.ModelOptionsResponse
 import com.m57.hermescontrol.data.model.ModelProvider
 import com.m57.hermescontrol.data.model.PluginInfo
@@ -895,7 +896,14 @@ class E2eIntegrationTest {
     fun testChannelsConfiguration_success() =
         runTest {
             val platform = MessagingPlatform("telegram", "Telegram", false, false, emptyList())
-            coEvery { mockApiService.getMessagingPlatforms() } returns Response.success(listOf(platform))
+            coEvery { mockApiService.getMessagingPlatforms() } returns
+                Response.success(
+                    MessagingPlatformResponse(
+                        env_path = "/tmp/.env",
+                        gateway_start_command = "hermes gateway start",
+                        platforms = listOf(platform),
+                    ),
+                )
             coEvery { mockApiService.configurePlatform("telegram", any()) } returns Response.success(Unit)
 
             val viewModel = ChannelsViewModel()