Epic: ORB review-comment redesign + config-as-code cleanup

[JSONbored]

Tracking epic for a redesign of the converged PR review comment (src/review/unified-comment.ts) plus a cleanup pass on the .loopover.yml config surface that drives it. Grew out of a direct request to make the comment lead with what's actually decision-relevant (disposition, blockers, AI fix context) and demote/collapse everything advisory-only, plus untangle the config duplication that makes review.fields hard to find/maintain.

Landing as a sequence of small, independently-tested PRs rather than one large change.

Scope

• review: drop redundant square banner + demote readiness chip on non-ready verdicts #6066 -- drop redundant square banner + demote readiness chip on non-ready verdicts
• review: collapse the 9-row signal table into decision-driver chips + one advisory fold #6067 -- collapse the 9-row signal table into decision-driver chips + one advisory fold
• review: wire per-blocker AI fix-context (CodeRabbit-style), not just one whole-PR prompt #6068 -- wire per-blocker AI fix-context (CodeRabbit-style)
• config: merge the split review: block in .loopover.yml.example #6071 -- merge the split review: block in .loopover.yml.example
• config: codegen the review.fields doc block instead of 7 hand-synced copies #6070 -- codegen the review.fields doc block instead of 7 hand-synced copies
• review: aggregate size-budget guard across optional comment collapsibles #6069 -- aggregate size-budget guard across optional comment collapsibles
• chore: fix gittensory -> loopover rename residue #6074 -- rename residue cleanup (gittensory -> loopover stragglers)
• investigate: is the legacy comment renderer still needed anywhere? #6073 -- investigate whether the legacy comment renderer is still needed anywhere

Not a contributor-facing change; owner-only work.

[linear-code]

JSO-4177