Add EdzImporter + collection-panel import action (M2)

Wires EPLAN .edz import into the elements panel. EdzImporter orchestrates
EdzArchive -> EdzPart -> EdzElementBuilder and writes the generated .elmt into a
destination collection folder (named by order number). A right-click
"Importer une piece EPLAN (.edz)..." action on a writable collection directory
opens a file picker, runs the importer into that folder's fileSystemPath() and
reloads the panel; errors surface via QetMessageBox. Modeled on newElement().

EdzImporter verified headless against the Python oracle for KG6000/MFH200/
R1D200; the panel wiring is built/tested via the WSL Qt5+KF5 build.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sources/import/edz/edzimporter.h

@@ -0,0 +1,45 @@
+/*
+	Copyright 2006 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech. If not, see <http://www.gnu.org/licenses/>.
+*/
+#ifndef EDZIMPORTER_H
+#define EDZIMPORTER_H
+
+#include <QString>
+
+/**
+	@brief Orchestrates importing an EPLAN .edz package as a QET element.
+
+	Ties together EdzArchive (extract) -> EdzPart (parse) -> EdzElementBuilder
+	(build) and writes the resulting .elmt into a destination collection folder.
+	UI-decoupled so it stays unit-testable headless; the collection widget calls
+	importToDirectory() and then refreshes the panel.
+*/
+class EdzImporter
+{
+	public:
+		bool importToDirectory(const QString &edz_path,
+				       const QString &dest_dir);
+
+		QString writtenPath() const { return m_written; }
+		QString errorString() const { return m_error; }
+
+	private:
+		QString m_written;
+		QString m_error;
+};
+
+#endif // EDZIMPORTER_H