Add wIRC main scrollback, route services to it, remember window bounds, bump to 0.1.7

wIRC main scrollback
- The main window now has a "Server messages" scrollback using the same
  rendering and stick-to-bottom code as channel windows (extracted from
  ChannelScreen into a shared MessageScrollback composable).
- MOTD, numerics, errors, connection status, user modes, INVITE, ERROR,
  non-ACTION CTCP requests and notices/messages from services
  (NickServ, ChanServ, *Serv, Global, ...) and the server go there. Its
  history persists like any other buffer (history/wirc-main__main.json).
- Unread indicator: lines arriving while the main window is unfocused
  show as "N new" next to the label and in the window title/taskbar.

Private messages and /whois
- A PM or notice from a real user opens its query window, and reopens it
  if it was closed. Services and the server no longer open windows.
- /whois <nick> sends WHOIS and shows the formatted reply in the window
  it was typed in, or in wIRC main if that window has since closed.
- /me now sends a proper CTCP ACTION (the \x01 wrapper was missing).

Window position and size
- Main, channel and PM windows remember position and size in
  window_prefs.json under the existing "<serverId>__<name>" key (main
  uses "wirc-main__main"). The new windowX/windowY/windowWidth/
  windowHeight fields are optional, so older files still load.
- A saved position is only used if the window's title strip is on a
  connected monitor; otherwise, and for windows with no saved position,
  windows cascade from the primary screen's top-left with a 32dp offset.
- window_prefs.json is now written via a temp file + atomic move.

Cleanup
- Remove the TEMP DEBUG aliasDebug tracing, ServerRepository.upsert
  printlns and connmgr-debug printlns.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/main/kotlin/ui/MainScreen.kt

@@ -1,5 +1,7 @@
 package ui
 
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
@@ -11,7 +13,9 @@ import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.focus.FocusDirection
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalFocusManager
+import androidx.compose.ui.platform.LocalWindowInfo
 import androidx.compose.ui.input.key.Key
 import androidx.compose.ui.input.key.KeyEventType
 import androidx.compose.ui.input.key.isShiftPressed
@@ -23,9 +27,12 @@ import androidx.compose.ui.unit.DpSize
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.window.DialogWindow
 import androidx.compose.ui.window.rememberDialogState
+import data.MAIN_BUFFER_KEY
 import data.ServerConfig
 import data.ServerRepository
+import data.WindowDisplaySettings
 import irc.ConnectionManager
+import irc.mircPalette
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 
@@ -33,8 +40,10 @@ import kotlinx.coroutines.launch
 fun MainScreen(
     repo: ServerRepository,
     colorScheme: ColorScheme,
+    displaySettings: WindowDisplaySettings,
     onOpenChannel: (serverId: String, channelName: String) -> Unit,
-    onExitApp: () -> Unit
+    onExitApp: () -> Unit,
+    onUnreadChange: (Int) -> Unit
 ) {
     var servers by remember { mutableStateOf(repo.loadAll()) }
     var showAddDialog by remember { mutableStateOf(false) }
@@ -44,6 +53,26 @@ fun MainScreen(
     var openedChannels by remember { mutableStateOf(mapOf<String, List<String>>()) }
     val coroutineScope = rememberCoroutineScope()
 
+    val buffers by ConnectionManager.buffers.collectAsState()
+    val mainMessages by remember { derivedStateOf { buffers[MAIN_BUFFER_KEY]?.messages ?: emptyList() } }
+    val textColor = mircPalette[displaySettings.textColorMircIndex]
+
+    // Unread indicator: lines that arrived in wIRC main while this window didn't have focus
+    // (e.g. while typing in a channel window). Shown next to the "Server messages" label and,
+    // via onUnreadChange, in the window title / taskbar. Cleared as soon as the window is
+    // focused. Compared by timestamp rather than count so history loaded at startup never
+    // counts as new.
+    val windowFocused = LocalWindowInfo.current.isWindowFocused
+    var lastSeenMillis by remember { mutableStateOf(System.currentTimeMillis()) }
+    val newest = mainMessages.lastOrNull()
+    LaunchedEffect(windowFocused, newest?.seq) {
+        if (windowFocused) {
+            lastSeenMillis = maxOf(lastSeenMillis, newest?.timestampMillis ?: 0L, System.currentTimeMillis())
+        }
+    }
+    val unread = if (windowFocused) 0 else mainMessages.count { it.timestampMillis > lastSeenMillis }
+    LaunchedEffect(unread) { onUnreadChange(unread) }
+
     Column(modifier = Modifier.fillMaxSize().padding(16.dp)) {
         Row(
             modifier = Modifier.fillMaxWidth(),
@@ -125,6 +154,34 @@ fun MainScreen(
                 Spacer(Modifier.height(12.dp))
             }
         }
+
+        Spacer(Modifier.height(8.dp))
+        Row(verticalAlignment = Alignment.CenterVertically) {
+            Text("Server messages", style = MaterialTheme.typography.labelMedium)
+            if (unread > 0) {
+                Spacer(Modifier.width(8.dp))
+                Text(
+                    "\u25CF $unread new",
+                    color = UNREAD_INDICATOR_COLOR,
+                    style = MaterialTheme.typography.labelMedium
+                )
+            }
+        }
+        Spacer(Modifier.height(4.dp))
+        // MOTD, numerics, errors, services/server notices and WHOIS replies whose window
+        // is gone - see ConnectionManager. Same rendering and auto-scroll as a channel window.
+        MessageScrollback(
+            messages = mainMessages,
+            displaySettings = displaySettings,
+            textColor = textColor,
+            isMention = { false },
+            modifier = Modifier
+                .weight(1f)
+                .fillMaxWidth()
+                .background(Color.Black.copy(alpha = displaySettings.backgroundAlpha))
+                .border(1.dp, Color.Gray.copy(alpha = 0.5f))
+                .padding(vertical = 2.dp)
+        )
     }
 
     if (showAddDialog) {
@@ -141,6 +198,8 @@ fun MainScreen(
     }
 }
 
+private val UNREAD_INDICATOR_COLOR = Color(0xFFFFA500)
+
 @Composable
 private fun ServerCard(
     server: ServerConfig,