This PR introduces cross-platform support for launching external binaries (`ace-lm` and `ace-synth`) on Windows systems.
**Key changes:**
* Introduced `EXE_EXT` constant in `AceStepWorker.h` using `Q_OS_WIN` macro to handle `.exe` extensions automatically.
* Updated binary path construction to ensure `QFileInfo::isExecutable()` and `QProcess` work correctly on Windows.
* The code remains fully compatible with Linux/macOS (extension remains empty).
**Why this is needed:**
On Windows, `QProcess` and `QFileInfo` require the `.exe` suffix to correctly identify and execute binary files. Without this change, the application fails to find the required tools even if they are present in the directory.
In acestep.cpp since commit 1e627bf, binary file names changed:
- ace-qwen3 --> ace-lm
- dit-vae --> ace-synth
! For users of previous aceradio versions:
- Delete settings for re-configuration
- Binaries rebuild with new names
acestep.cpp previously generated *.wav by default for maximum quality.
Later changed to mp3, but aceradio expects WAV input.
- Revert to WAV default to match aceradio workflow
- No conversion overhead or compatibility issues
- Preserves original high-quality generation logic
