backstage release v0.122.0

Added

• Add optional guest auth provider, enabled via ENABLE_GUEST_AUTH environment variable.
• Add optional aiChat.systemPrompt config to override the built-in AI chat system prompt.
• Add optional aiChat.openai.api config to target OpenAI-compatible servers via chat completions API.

Changed

• Update Backstage to 1.50.2.
• Migrate scaffolder pages to NFS SubPageBlueprint layout.
• Make sidebar nav items configurable via NFS extensions.
• Use custom X-Backstage-Token header for identity tokens to avoid conflicts with ingress-level Basic auth.
• Use ProxiedSignInPage with guest provider as fallback when Dex auth is not configured.
• Allow hiding the Backstage Identity card on the settings general page via extension config.

Fixed

• Fix AI chat producing empty replies when the model uses a tool by increasing the default step limit.
• Strip stale tool results from AI chat conversation history to reduce token usage. See ./docs/releases/v0.122.0-changelog.md for more information.