Add PR-ready change review reports

[sameer2191]

Summary

• Add review-report / pr-report CLI output for PR-ready Markdown or JSON change-impact reports.
• Add the change_review_report MCP tool so agents can generate the same review artifact from graph context.
• Improve detect_changes precision by asking Git for all untracked files, so security-sensitive paths such as workflow files are reported at file granularity.
• Document the workflow in README, docs/agent-guide.md, docs/research-notes.md, and llms.txt.

Validation

• npm run verify
• npm run test:skip-gate
• npm run package:check
• npm run installer:audit
• npm pack --dry-run
• npm audit --omit=dev
• CLI smoke: self-indexed to /private/tmp/repolens-pr-review.db, generated Markdown and JSON review reports, and confirmed Markdown starts with # RepoLens Change Review

Notes

• The dashboard smoke remains covered by the existing skip policy in this sandbox because the local test environment cannot bind a dashboard port.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Default the report database to the selected repo

When review-report / change_review_report is run with a root outside the current working directory and no explicit --db/dbPath, this passes undefined through to detectChanges, so withStore opens the current directory's default .repolens/memory.db instead of the selected repo's default database. A common flow like repolens-mcp index /tmp/app followed by repolens-mcp review-report /tmp/app from another directory will therefore generate a report against the wrong graph or mark everything unindexed; default the DB to defaultDbPath(root) when a root is provided and no DB is supplied.

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