fix: add Windows compatibility for make dev/start commands (#1297)

* fix: add Windows compatibility for make dev/start commands

On Windows with MinGW/Git Bash, the Makefile's direct shell script
execution fails with 'CreateProcess(NULL, env bash ...)' error.

This fix:
- Detects Windows via $(OS) == Windows_NT
- Uses explicit bash invocation on Windows
- Falls back to direct execution on Unix

Users need Git Bash installed (comes with Git for Windows).

Fixes #1288
Related #1278

* Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>