Trim CLAUDE.md from 792 to 160 lines

[igerber]

Summary

• Rewrite CLAUDE.md from 792 → 160 lines (80% reduction) to improve instruction-following quality
• Extract 6 development checklists + grep patterns to .claude/commands/dev-checklists.md (accessible via /dev-checklists)
• Extract documentation requirements + test writing guidelines to CONTRIBUTING.md
• Update cross-references in review-plan.md, docs-check.md, and check-plan-review.sh
• Remove discoverable content: module structure listing, performance architecture, benchmark docs, test structure listing

Methodology references (required if estimator / math changes)

• N/A — no methodology changes

Validation

• Tests added/updated: No test changes (documentation-only refactor)
• No runtime code modified — CLAUDE.md, command files, and hook are agent instructions only

Security / privacy

• Confirm no secrets/PII in this PR: Yes

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Generated with Claude Code

[github-actions]

Overall assessment: ✅ Looks good

Executive Summary

• Documentation-only refactor; no estimator, math, inference, or runtime code paths changed in the diff.
• References updated to point documentation requirements to CONTRIBUTING.md and development checklists to .claude/commands/dev-checklists.md, with review-plan and hook messaging aligned (.claude/commands/docs-check.md:L198-L205, .claude/commands/review-plan.md:L74-L86, .claude/hooks/check-plan-review.sh:L16-L33).
• No tests needed for a doc-only change; new contributor guidance centralized (CONTRIBUTING.md:L1-L77).

Methodology

• No findings. No estimator/math/SE/inference changes in this PR, so docs/methodology/REGISTRY.md cross-check is not applicable.

Code Quality

• No findings.

Performance

• No findings.

Maintainability

• No findings.

Tech Debt

• No findings.

Security

• No findings.

Documentation/Tests

• No findings. Doc changes are internally consistent across updated command docs and contributor guidance.