Improve Windows Build Experience: vcpkg dependency and default binary

[bardo84]

Hello! I tried building runmat on Windows and encountered a few hurdles that could be smoothed out for new contributors.

1. Missing vcpkg Dependency (OpenBLAS)
   When running cargo check or cargo build on Windows, the build fails if vcpkg is not installed/configured because runmat-runtime depends on openblas-src (via the default blas-lapack feature).

Error:

VcpkgNotFound("No vcpkg installation found. Set the VCPKG_ROOT environment variable...")
Suggestion: It would be helpful to:

Mention this requirement clearly in the
README.md
or CONTRIBUTING.md.
Or, consider making the blas-lapack feature optional by default on Windows?
Or, provide a "Getting Started" command that builds without it (e.g., cargo run --no-default-features --features gui,wgpu).
2. Ambiguous cargo run
Running cargo run fails because there are multiple binaries in the workspace (export_builtins, runmat, etc.).

Error:

error: cargo run could not determine which binary to run. Use the --bin option to specify a binary...
Suggestion: Add default-run = "runmat" to the [package] section of
runmat/Cargo.toml
(or the workspace
Cargo.toml
if applicable, though usually per-package).

Summary
I managed to get it running with:

cargo run --bin runmat --no-default-features --features gui,wgpu -- info
But making these small tweaks would improve the "clone and run" experience significantly!

Thanks for the great project!