refactor(skills): cut boilerplate and dead conventions from rendered workflows

[alexeyv]

Summary

Stacked on #3060; merge that first. GitHub retargets this PR to dev when its base merges.

Four commits, each deleting prose the agent no longer needs on every run:

• Cut the boilerplate from bmad-code-review/workflow.md. The goal paragraph, the snapshot warning, the architecture block, the step-processing and critical-rules lists, and the three activation sub-headings are gone. The workflow now says what the reviewers do, keeps the subagent instruction, and lists two conventions.
• Define {project-root} in SKILL.md, where it is first resolved. The four rendered skills and the toolsmith template say it is the nearest folder containing _bmad/, from the working directory upward, next to the command that uses it. The duplicate definition in each workflow.md is removed.
• Drop the {date} definition. Its uses make its meaning obvious.
• Drop the absolute-path convention. Every cross-file reference in a rendered snapshot is already an absolute path the agent can see; the rule had nothing left to guard.

Verification

• uv run tools/validate_skills.py --strict: zero findings.
• uv run --frozen python -B -m pytest: passes.
• bmad-code-review rendered in a worktree: the trimmed workflow comes out with no leaked tokens.

[greptile-apps]

Confidence Score: 5/5

[Low risk] Documentation and workflow instruction text refactored.

The PR appears safe to merge; no actionable regression was identified.

Summary

The PR moves project-root discovery guidance to skill entry points and removes repeated conventions and workflow boilerplate.

• The code-review workflow retains its activation order and first-step link.
• Rendered cross-file references remain backed by the renderer.

_{Reviews (1) · Last reviewed commit: "docs(skills): drop the absolute-path con..."}