chore: release 0.2.1 - widen @oven/bun-* version range (#176)

* fix: widen @oven/bun-* version range to improve install compatibility

Lower the minimum version of @oven/bun-* optional dependencies from
^1.3.4 to ^1.2.21. This is the lowest common version available across
all platform-specific packages, improving compatibility for contributors
who may not have access to the latest package versions.

The caret range (^) still allows npm to install newer versions when
available.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* chore: bump version to 0.2.1

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

scripts/setup-bun.mjs

@@ -108,7 +108,7 @@ function findBunBinary() {
 async function downloadBunForWindowsArm64() {
   // Windows ARM64 can run x64 binaries via emulation
   const pkg = "bun-windows-x64-baseline";
-  const version = "1.3.4";
+  const version = "1.2.21";
   const url = `https://registry.npmjs.org/@oven/${pkg}/-/${pkg}-${version}.tgz`;
   const destDir = join(nodeModules, "@oven", pkg);