feat: add general compare mode

[ccf]

Summary

• add a new compare mode page for teams, engineers, projects, and time periods
• add a shared compare analytics endpoint and snapshot response for unified side-by-side metrics and workflow mix
• true up the roadmap for personal impact review, website positioning, and the new general compare mode

Testing

• PYTHONPATH=src pytest tests/test_compare.py -q
• ruff check src/primer/common/schemas.py src/primer/server/services/compare_service.py src/primer/server/routers/analytics.py tests/test_compare.py
• cd frontend && ./node_modules/.bin/tsc --noEmit
• cd frontend && ./node_modules/.bin/eslint src/pages/compare.tsx src/pages/tests/compare.test.tsx src/hooks/use-api-queries.ts src/components/layout/sidebar.tsx src/App.tsx
• cd frontend && ./node_modules/.bin/vitest run --run src/pages/tests/compare.test.tsx

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Note

Medium Risk
Introduces a new analytics endpoint and aggregation service that combines multiple metric sources and enforces role-based access, which could affect correctness/performance and authorization boundaries.

Overview
Adds a new Compare experience that lets leadership users compare teams, engineers, projects, or time periods side-by-side, including headline deltas and top workflow mix.

Implements GET /api/v1/analytics/compare with new CompareResponse schemas/types and a compare_service that builds snapshots from existing overview/productivity/quality/maturity/workspace data, computes deltas, and derives top workflows from workflow profiles; access is restricted (engineers blocked; team leads limited to their team and cannot do team-vs-team).

Wires the new page into the frontend router/sidebar, adds useCompareAnalytics, and includes frontend + backend tests for the new modes and authorization behavior.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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Duplicated snapshot-building logic across two functions

Low Severity

_build_period_snapshot and _build_team_snapshot have nearly identical bodies — both call the same four service functions (get_overview, get_productivity_metrics, get_quality_metrics, get_maturity_analytics) and construct a CompareSnapshot with the exact same field mappings. The only difference is how label is determined. If the snapshot field mappings ever need to change, both functions must be updated in lockstep, risking inconsistent bug fixes.

Additional Locations (1)

• src/primer/server/services/compare_service.py#L73-L126