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/data/Models.kt

@@ -47,6 +47,35 @@ data class IrcMessage(
 /** Buffer key: server id + channel/query name (channel names include '#'). */
 data class BufferKey(val serverId: String, val name: String)
 
+/**
+ * wIRC main's own buffer: server messages (MOTD, numerics, errors, whois fallback) and
+ * services/server notices from every connected server. Server ids are built from the host
+ * with every non-alphanumeric character replaced by '_' (see ServerEditDialog), so one can
+ * never contain '-' - this id can't collide with a real server. Also used as the
+ * window_prefs.json key ("wirc-main__main") for the main window's saved position and size.
+ */
+val MAIN_BUFFER_KEY = BufferKey("wirc-main", "main")
+
+// Nicks that are network services rather than people. Their PRIVMSGs and NOTICEs go to
+// wIRC main instead of opening a query window. Anything ending in "serv" is also treated
+// as a service, which covers the less common ones (MemoServ, HostServ, SaslServ, ...).
+private val KNOWN_SERVICE_NICKS = setOf("nickserv", "chanserv", "global", "alis", "q", "x")
+
+fun isServiceNick(nick: String): Boolean {
+    val lower = nick.lowercase()
+    return lower in KNOWN_SERVICE_NICKS || lower.endsWith("serv")
+}
+
+/**
+ * True when a message's source is a service or the server itself rather than a real user.
+ * A user prefix always has the "nick!user@host" form; a missing prefix or one without '!'
+ * is a server name (e.g. "irc.rizon.io").
+ */
+fun isServiceOrServerPrefix(prefix: String?): Boolean {
+    if (prefix == null || !prefix.contains('!')) return true
+    return isServiceNick(prefix.substringBefore('!'))
+}
+
 data class ChannelUser(
     val nick: String,
     val isOp: Boolean = false,