Swap: tell the user when a journal is locked out or failing; long names

- SwapManager queues user notices when a journal is held by another kte
  (this session's edits are then not journaled) and, once per gap, when
  journal writes fail. Editor shows them in the status line from its
  per-frame hook. Both went only to the error log, so crash recovery was
  silently off or incomplete.
- The fallback swap name '<basename>.<hash>.swp' exceeded NAME_MAX for
  basenames over ~233 bytes, so such files were never journaled; the
  basename is shortened (on a UTF-8 boundary) only in that case.
- Audit doc: sixth-round findings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB

Editor.cc

@@ -495,8 +495,11 @@ Editor::ProcessPendingOpens()
 	try {
 		// Also the once-per-frame hook for the journal: retry the
 		// checkpoint of a journal that lost a record.
-		if (kte::SwapManager *sm = Swap())
+		if (kte::SwapManager *sm = Swap()) {
 			sm->RetryGapCheckpoints();
+			if (std::string notice = sm->TakeUserNotice(); !notice.empty())
+				SetStatus(notice);
+		}
 		return process_pending_opens_();
 	} catch (const std::exception &e) {
 		kte::ErrorHandler::Instance().Error("Editor", std::string("open failed: ") + e.what(), "");