v0.5.0

Added

• A tier-agent-spawns hook (PreToolUse on Agent) applies the delegation stance to every
  subagent spawn that names no agent definition and no model, which is what a planning
  framework's or a plugin's "launch a subagent" produces: one tier below the session under
  tiered, untouched under session-model, a prompt under off. Frontmatter and explicit
  model choices are left alone. Inside a repository that carries a framework runtime
  (_bmad/scripts/ or _bmad/core/), a bare spawn keeps the session model: the framework's
  lenses are judgment work its overrides cannot rename, and its own rule is same capability.
• templates/bmad/custom/ carries override files in BMad's own format for bmad-build,
  bmad-build-auto and bmad-code-review that run their review layers as the reviewer and
  spec-reviewer agents and the implementation handoff on the builder's tier. harness bmad apply installs them into a repository's _bmad/custom/, skipping a template whose keys or
  layer ids the installed skill no longer declares, and harness bmad check reports that drift.
  The harness-session hook runs apply for the repository a session starts in and says so
  once when it wrote, kept or skipped a file.
• docs/bmad.md records how the two pieces keep the delegation stance in charge of a
  framework's spawns, and why the implementation handoff is not routed to builder.