Claude Code 2.1.123 — fix for OAuth 401-loop and Bedrock service tier

Anthropic released Claude Code 2.1.123 (April 29) and 2.1.122 (April 28). Highlights: fixed an infinite OAuth 401 loop with CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1; a new ANTHROPIC_BEDROCK_SERVICE_TIER variable (default | flex | priority) for selecting an Amazon Bedrock tier via the X-Amzn-Bedrock-Service-Tier header; pasting a PR URL into /resume now finds the session that created that PR (GitHub, GitHub Enterprise, GitLab, Bitbucket); /mcp highlights claude.ai connectors hidden by a manually added server with the same URL; OpenTelemetry — numeric api_request/api_error attributes are now emitted as numbers, and a claude_code.at_mention event was added. Continuation of the v2.1.121 release chain.