Bundle LZMA SDK for .edz extraction; drop 7z CLI dependency (M3)

Replaces the QProcess->7z shim with the public-domain LZMA SDK (23.01) 7-Zip
reader, vendored under sources/import/edz/lzma/ (decode-only subset). New
edzsevenzip.cpp wraps SzArEx_Open/SzArEx_Extract and writes entries via Qt, so
EdzArchive no longer needs an external 7-Zip at runtime. Enables the C language
in CMake for the vendored sources.

Verified: the bundled decoder extracts all three ifm sample .edz and the
generated elements still match the Python oracle exactly (byte-correct decode),
with no 7z on the path.

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

sources/import/edz/lzma/7zCrc.h

@@ -0,0 +1,27 @@
+/* 7zCrc.h -- CRC32 calculation
+2023-04-02 : Igor Pavlov : Public domain */
+
+#ifndef ZIP7_INC_7Z_CRC_H
+#define ZIP7_INC_7Z_CRC_H
+
+#include "7zTypes.h"
+
+EXTERN_C_BEGIN
+
+extern UInt32 g_CrcTable[];
+
+/* Call CrcGenerateTable one time before other CRC functions */
+void Z7_FASTCALL CrcGenerateTable(void);
+
+#define CRC_INIT_VAL 0xFFFFFFFF
+#define CRC_GET_DIGEST(crc) ((crc) ^ CRC_INIT_VAL)
+#define CRC_UPDATE_BYTE(crc, b) (g_CrcTable[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
+
+UInt32 Z7_FASTCALL CrcUpdate(UInt32 crc, const void *data, size_t size);
+UInt32 Z7_FASTCALL CrcCalc(const void *data, size_t size);
+
+typedef UInt32 (Z7_FASTCALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
+
+EXTERN_C_END
+
+#endif