feat(holmes): make PR comments plain-English and glossary-backed

[flyingrobots]

Sponsor actor

A pull-request reviewer who needs to decide whether a change is safe to merge without already knowing Wesley/HOLMES jargon.

Hill

A reviewer can read the HOLMES GitHub comment and understand the ship recommendation, the top reasons, the next actions, and the jargon from the comment alone.

Playback

Open a PR with a HOLMES comment and understand, without opening source code or docs:

• safe / investigate / do not ship
• why
• what to do next
• what SCS / TCI / MRI / evidence trust mean

Type

product

Invariants

• keep the underlying report truthful
• do not hide failing gates or weak evidence
• keep the GitHub comment machine-generated and reproducible
• do not break existing JSON report contracts

Non-goals

• redesign the CLI markdown report wholesale
• remove the Holmes/Watson/Moriarty flavor
• change SHIPME or certificate policy

Acceptance

• the PR comment starts with a plain-English summary
• the visible summary avoids unexplained acronyms
• the comment includes actionable next steps
• a collapsed glossary defines the major HOLMES terms
• tests cover the comment-builder behavior