Add loading indicator, error display, archived memos API

Loading state:
- CircularProgressIndicator shown during first fetch instead of
  "no memos yet". isInitialLoading flag in MemoListUiState cleared
  after first emission from observeMemos().

Error display:
- Failed refresh/load errors shown as red text in memo list
- Previously errors were captured but never displayed to user

Archived memos:
- listArchivedMemos() API endpoint added (filter: state == ARCHIVED)
- "view archived memos" link in explorer page (placeholder for full UI)

102 tests passing.

Co-Authored-By: Claude Opus 4.6 (1M context)

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>

composeApp/src/commonMain/kotlin/com/avinal/memos/api/MemosApiClient.kt

@@ -138,6 +138,13 @@ class MemosApiClient(
         }.body()
     }
 
+    suspend fun listArchivedMemos(): ApiResult<ListMemosResponse> = apiCall {
+        httpClient.get(url("/memos")) {
+            parameter("pageSize", 50)
+            parameter("filter", "state == \"ARCHIVED\"")
+        }.body()
+    }
+
     suspend fun deleteMemo(id: String): ApiResult<Unit> = apiCall {
         val response = httpClient.delete(url("/memos/$id"))
         if (!response.status.isSuccess()) {

composeApp/src/commonMain/kotlin/com/avinal/memos/ui/memos/MainScreen.kt

@@ -247,6 +247,14 @@ private fun ExplorerPage(
             )
         }
 
+        Spacer(Modifier.height(12.dp))
+        Text(
+            "view archived memos",
+            fontSize = 14.sp,
+            color = accent,
+            modifier = Modifier.clickable { /* navigate to archived */ }.padding(vertical = 4.dp),
+        )
+
         Spacer(Modifier.height(16.dp))
 
         Row(

composeApp/src/commonMain/kotlin/com/avinal/memos/ui/memos/MemoListScreen.kt

@@ -349,7 +349,13 @@ fun MemoListScreen(
                 )
             }
 
-            if (memos.isEmpty() && !uiState.isRefreshing) {
+            if (uiState.isInitialLoading && memos.isEmpty()) {
+                item {
+                    Box(Modifier.fillMaxWidth().padding(top = 48.dp), contentAlignment = Alignment.Center) {
+                        androidx.compose.material3.CircularProgressIndicator(color = accent, strokeWidth = 2.dp)
+                    }
+                }
+            } else if (memos.isEmpty() && !uiState.isRefreshing) {
                 item {
                     Box(Modifier.fillMaxWidth().padding(top = 48.dp), contentAlignment = Alignment.Center) {
                         Text("no memos yet", fontSize = 15.sp, color = subtleColor)
@@ -357,6 +363,15 @@ fun MemoListScreen(
                 }
             }
 
+            if (uiState.error != null) {
+                item {
+                    Text(
+                        uiState.error!!, fontSize = 12.sp, color = MaterialTheme.colorScheme.error,
+                        modifier = Modifier.padding(start = 24.dp, end = 12.dp, top = 4.dp, bottom = 4.dp),
+                    )
+                }
+            }
+
             items(memos, key = { it.id }) { memo ->
                 MemoCard(
                     memo = memo,

composeApp/src/commonMain/kotlin/com/avinal/memos/ui/memos/MemoListViewModel.kt

@@ -12,6 +12,7 @@ import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
@@ -22,6 +23,7 @@ data class MemoListUiState(
     val searchQuery: String = "",
     val isSearching: Boolean = false,
     val error: String? = null,
+    val isInitialLoading: Boolean = true,
 )
 
 class MemoListViewModel(private val memoRepository: MemoRepository) : ViewModel() {
@@ -32,6 +34,13 @@ class MemoListViewModel(private val memoRepository: MemoRepository) : ViewModel(
     private val _searchQuery = MutableStateFlow("")
     private var searchJob: Job? = null
 
+    init {
+        viewModelScope.launch {
+            memoRepository.observeMemos().first()
+            _uiState.update { it.copy(isInitialLoading = false) }
+        }
+    }
+
     val memos: StateFlow<List<Memo>> = combine(
         memoRepository.observeMemos(),
         _searchQuery,