fix(build-family): tag governance-file findings in deferred-work.md

[gmoncor]

What: Add a priority marker to the deferred-work.md entry format, used when a deferred finding's fix would edit agent-context files (CLAUDE.md, AGENTS.md, rules, etc).

Why: Today every deferred entry is written identically regardless of whether it's routine technical debt or a finding touching agent-context files, which this repo's own AGENTS.md treats as high cumulative-impact.

How:

• Update the deferred-work.md entry format documented in both step-04-review.md files to add the priority marker for this subtype.
• Apply identically to both bmad-build and bmad-build-auto's step-04-review.md.

Testing: Read-through diff of both files; doc-format-only change to a low-priority log, no gating/routing behavior changes.

🤖 Generated with Claude Code