Add native Bun debugger support

[zx8086]

Body

Summary

Zed's JavaScript debugger adapter doesn't work with Bun's WebKit Inspector Protocol. Breakpoints and debugger; statements are not hit when debugging
Bun applications.

Current behavior

• Using the JavaScript adapter with "runtimeExecutable": "bun" and "type": "pwa-node" connects but breakpoints don't pause execution
• debugger; statements in code are ignored
• Some configurations result in "debugger shutdown unexpectedly" errors

Expected behavior

Breakpoints set in Zed and debugger; statements should pause execution when debugging Bun applications.

Workaround

Bun's native web debugger works correctly:
bun --inspect-wait src/index.ts
This opens a Chrome DevTools interface at https://debug.bun.sh/... where breakpoints work as expected.

Environment

• Zed version: latest
• Bun version: 1.3.9
• OS: macOS

Additional context

Bun uses the WebKit Inspector Protocol on port 6499 by default, which differs from Node.js. The underlying vscode-js-debug adapter doesn't support Bun
natively (confirmed in #49033). A Bun-specific debug adapter would improve the experience for Bun users.