[BUG] Extension fails to activate on Windows — hardcoded Linux path in build (`file:///home/runner/work/...`)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

After auto-updating to v2.1.129, the Claude Code extension fails to activate on Windows with the following error:

TypeError: The argument 'filename' must be a file URL object, file URL string, or absolute path string.
Received 'file:///home/runner/work/claude-cli-internal/claude-cli-internal/build-agent-sdk/sdk.mjs'

The extension attempts to load sdk.mjs from a hardcoded Linux CI/build path (/home/runner/work/...) that does not exist on Windows machines. This causes activation to fail silently — the extension is stuck in "Activating..." state indefinitely with no user-facing error message.

Actual Behavior:
Extension fails to activate due to a Linux absolute path (file:///home/runner/work/claude-cli-internal/claude-cli-internal/build-agent-sdk/sdk.mjs) being hardcoded in extension.js at line 102.

Root Cause (suspected):
The build pipeline appears to have embedded an absolute Linux path for sdk.mjs instead of resolving it relative to the extension directory at runtime. This works in the CI/Linux environment but breaks on Windows.

What Should Happen?

Extension activates successfully on Windows as it did in previous versions.

Error Messages/Logs

Steps to Reproduce

1. Install or auto-update Claude Code extension to v2.1.129 on Windows
2. Open VS Code
3. Observe extension stuck on "Activating..."
4. Check extension host logs at exthost.log to see the error

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.129

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_