Fix worktree-new Rust backend rebuild: add maturin to dev deps and fix manifest path

[igerber]

Summary

• Add maturin>=1.4,<2.0 to [project.optional-dependencies] dev so maturin is available in the venv for Rust code rebuilds
• Fix manifest path in worktree-new step 6 from $WORKTREE_PATH/Cargo.toml to $WORKTREE_PATH/rust/Cargo.toml
• Clarify step 6 description: step 5 (pip install -e ".[dev]") already builds the Rust extension; step 6 verifies maturin works for future rebuilds

Methodology references (required if estimator / math changes)

• N/A - no methodology changes (build tooling and slash command only)

Validation

• Tests added/updated: No test changes (build config and command template only)
• Manual verification: confirmed rust/Cargo.toml exists and Cargo.toml does not exist at repo root

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

• No estimator, weighting, variance/SE, or identification logic changes; methodology registry unaffected for this PR. (docs/methodology/REGISTRY.md:L1-L200)
• Changes are limited to worktree setup docs and a dev-only maturin dependency; edge‑case checklist not triggered. (.claude/commands/worktree-new.md:L92-L116, pyproject.toml:L39-L47)
• No tests updated, which is reasonable for build-tooling/docs-only changes. (.claude/commands/worktree-new.md:L92-L116)

Methodology

• P3 (Info) Impact: No estimator/math/variance/assumption changes in the diff; registry and in‑code method references remain unchanged for this PR. Fix: None. (docs/methodology/REGISTRY.md:L1-L200, .claude/commands/worktree-new.md:L92-L116, pyproject.toml:L39-L47)

Code Quality

• P3 (Info) Impact: No production code changes; only docs/dev deps updated. Fix: None. (.claude/commands/worktree-new.md:L92-L116, pyproject.toml:L39-L47)

Performance

• P3 (Info) Impact: No runtime paths affected. Fix: None. (pyproject.toml:L39-L47)

Maintainability

• P3 (Info) Impact: Worktree instructions now use the correct Rust manifest path and clarify maturin usage, reducing setup confusion. Fix: None. (.claude/commands/worktree-new.md:L104-L116)

Tech Debt

• P3 (Info) Impact: No tech debt introduced. Fix: None. (.claude/commands/worktree-new.md:L92-L116, pyproject.toml:L39-L47)

Security

• P3 (Info) Impact: Dev-only dependency addition; no secrets or sensitive changes in diff. Fix: None. (pyproject.toml:L39-L47)

Documentation/Tests

• P3 (Info) Impact: Documentation updated; no tests changed, acceptable for build tooling/docs-only updates. Fix: None. (.claude/commands/worktree-new.md:L92-L116)