feat: MSVC auto-detection + C compiler check before torch.compile

[JamesNyeVRGuy]

MSVC auto-detection + C compiler check before torch.compile

torch.compile needs a C compiler (cl.exe on Windows, gcc on Linux). On Windows, Visual Studio Build Tools installs cl.exe but doesn't add it to PATH — users get a cryptic compilation failure and fall back to eager mode (~30% slower) without knowing why.

• Auto-detect MSVC in standard Visual Studio 2019/2022 install locations
• Check for C compiler before attempting compile
• Show actionable message with install link if missing
• Skip reasons are logged clearly instead of generic "compilation failed"

What does this change?

Replaces the simple skip_compile boolean with a prerequisite check that:

1. On Windows: searches for cl.exe in VS install paths and adds it to PATH automatically
2. If no compiler found: logs a clear message with install link instead of attempting compile and failing cryptically
3. On Linux: checks for gcc/cc before attempting compile

Only touches CorridorKeyModule/inference_engine.py. No new dependencies.

How was it tested?

• Tested on Windows with VS Build Tools installed (cl.exe auto-detected, compile succeeds)
• Tested on Windows without VS Build Tools (clear skip message logged, falls back to eager)
• Tested on Linux with gcc (compile succeeds as before)
• Tested on Linux Docker without gcc (clear skip message, falls back to eager)

Checklist

• uv run pytest passes
• uv run ruff check passes
• uv run ruff format --check passes