1. Add Windows AArch64 cross-compilation support via CI jobs
Introduce new CI configurations for cross-compiling to Windows ARM64 using Debian12Wine, FEX, and MSYS2.
Configure toolchain variables for LLVM MinGW and Wine emulation in CI pipelines.

2. Adjust compiler and RTS for AArch64 Windows compatibility
Reserve register `x18` on Windows and Darwin platforms in AArch64 codegen.
Handle Windows-specific relocations and data sections in AArch64 assembler.
Update PEi386 linker to recognize ARM64 binaries and support exception handling.
Adjust LLVM target definitions and data layouts for new architectures.
Update `ghc-toolchain` and build scripts to handle `TablesNextToCode` on Windows ARM64.

3. Enhance CI scripts and stability
Modify `ci.sh` to handle mingw cross-targets, fixing GHC executable paths and test execution.
Use `diff -w` in tests to ignore whitespace differences, improving cross-platform consistency.

4. Refactor and clean up code
Remove ...