chore: eliminate all Kotlin compiler warnings in main source (#877)

* chore: eliminate all Kotlin compiler warnings in main source

* test(chat): fix cross-class coroutine leaks poisoning the unit suite

- ChatUpdateCommandTest: inject FakeSlashUsageStore — the real DataStore
  store inits on real IO threads with a relaxed-mock app (cacheDir NPE)
  and leaks an uncaught exception into the next runTest class.
- ChatUpdateCommandTest + SlashCommandDispatchRpcTest: mock
  ProfileSwitchCoordinator.switched (ChatViewModelTest pattern) — VMs
  otherwise park collectors on the singleton flow that crash later
  classes (ProfileSwitchCoordinatorTest) on stale-Main resumption.

Full suite: 944 tests, 0 failures (was 2 flaky per run).

---------

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

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt

@@ -2890,7 +2890,7 @@ class ChatViewModel(
             if (lastAssistantIdx >= 0) {
                 val target = mapped[lastAssistantIdx]
                 if (target.reasoningText.isBlank()) {
-                    mapped[lastAssistantIdx] = target.copy(reasoningText = pendingReasoning!!)
+                    mapped[lastAssistantIdx] = target.copy(reasoningText = pendingReasoning)
                 }
             }
         }

app/src/main/java/com/m57/hermescontrol/ui/chat/components/ChatComposer.kt

@@ -28,9 +28,9 @@ import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.BasicTextField
 import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.InsertDriveFile
 import androidx.compose.material.icons.automirrored.filled.Send
 import androidx.compose.material.icons.filled.Close
-import androidx.compose.material.icons.filled.InsertDriveFile
 import androidx.compose.material3.DropdownMenu
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.Icon
@@ -405,7 +405,7 @@ fun AttachmentChip(
                 Spacer(modifier = Modifier.width(4.dp))
             } else {
                 Icon(
-                    imageVector = Icons.Default.InsertDriveFile,
+                    imageVector = Icons.AutoMirrored.Filled.InsertDriveFile,
                     contentDescription = attachment.name,
                     modifier = Modifier.size(24.dp),
                     tint = MaterialTheme.colorScheme.onSurfaceVariant,

app/src/main/java/com/m57/hermescontrol/ui/chat/tool/ToolViewBuilder.kt

@@ -90,7 +90,7 @@ object ToolViewBuilder {
             raw = firstString(parseMaybeObject(value), listOf("context"))
         }
 
-        return compactPreview(raw ?: "", max)
+        return compactPreview(raw, max)
     }
 
     private fun contextValue(value: JsonElement?): String {
@@ -1328,8 +1328,8 @@ object ToolViewBuilder {
         val elements = result?.get("elements") as? JsonArray
         if (elements != null) {
             val mode = firstString(result, listOf("mode"))
-            val width = intValue(result?.get("width"))
-            val height = intValue(result?.get("height"))
+            val width = intValue(result.get("width"))
+            val height = intValue(result.get("height"))
             val modePart = mode.takeIf { it.isNotEmpty() }?.let { " ($it)" } ?: ""
             val sizePart = if (width != null && height != null) " ${width}x$height" else ""
             return "${elements.size} elements$modePart$sizePart"