[BUG] Bedrock Bearer Token (ABSK) authentication broken in v2.1.94

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?

## Environment

• Claude Code version: 2.1.94 (broken), 2.1.92 (works)
• OS: Ubuntu Linux (x86_64)
• Auth method: AWS_BEARER_TOKEN_BEDROCK (ABSK token)
• CLAUDE_CODE_USE_BEDROCK=1
• AWS_REGION=us-west-2

## Description

Bedrock Bearer Token (ABSK) authentication stopped working in v2.1.94.
The same token and environment works fine with v2.1.92.

## Error

After entering interactive mode, every message returns:
403 {"Message":"Authorization header is missing"}

## Verification

• Direct curl to bedrock-runtime.us-west-2.amazonaws.com with the same Bearer token returns HTTP 200 — the token is valid.
• strace shows v2.1.94 first attempts to connect to api.anthropic.com (which gets ECONNRESET in our corporate network), then falls back to Bedrock but fails with 403.
• With --bare flag, api.anthropic.com call is skipped, but 403 still occurs.
• v2.1.92 binary with identical environment variables works correctly.

## Workaround

Pin to v2.1.92:
```bash
ln -sf ~/.local/share/claude/versions/2.1.92 ~/.local/bin/claude

---

What Should Happen?

It should work without 403 error

Error Messages/Logs

Steps to Reproduce

## Reproduction

1. Set AWS_BEARER_TOKEN_BEDROCK, CLAUDE_CODE_USE_BEDROCK=1, AWS_REGION
2. Run claude (v2.1.94) → enter interactive mode → send any message → 403
3. Run /home/.../.local/share/claude/versions/2.1.92 -p "hello" → works

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.94

Platform

AWS Bedrock

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_