backstage release v0.134.0

Muster: add workflow visualization. A new muster page renders muster workflow definitions as flow diagrams (one node per step, dashed condition edges) with execution history and live per-step status overlay. Backed by a new muster backend plugin that proxies the muster MCP server’s core_workflow_* tools over REST, reusing the aiChat.mcp entry named muster for connection config. See ./docs/releases/v0.134.0-changelog.md for more information.