Desktop: a --memory session writes no log file (#286 with #288)

#288 made --memory sessions write nothing (issue #164); #286's log file
would have been the exception. It is not opened there.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01912WaK6Rmew3wxZuPyX7E8

apps/lightcraft/src/main.rs

@@ -514,7 +514,8 @@ fn main() -> eframe::Result {
     // The log file: opened after the arguments, so `--version`, `--help` and a usage error leave
     // no file behind. Records logged until now are written to it first.
     if let Some(logger) = logger {
-        match log_dir() {
+        // a --memory session writes nothing (issue #164), a log file included
+        match log_dir().filter(|_| !in_memory) {
             Some(dir) => match logger.attach_dir(&dir) {
                 Ok(path) => log::info!("LightCraft {}, log file {}", env!("CARGO_PKG_VERSION"), path.display()),
                 // The file sink has given up by now, so this goes to standard error only.