feat: add per-status package counts to list endpoint (CM-1245)

[gaspergrom]

Summary

• Adds getPackageStatusCounts to the DAL (osspckgs/api.ts) — returns a count breakdown by all stewardship statuses for the currently active filters (excluding the status filter itself)
• The listPackages API endpoint now fires both queries in parallel via Promise.all and returns statusCounts alongside the existing paginated rows
• Enables the frontend tab bar to always show counts for every status tab while respecting ecosystem, lifecycle, health band, vuln severity, stale, unstewareded, and bus-factor filters

Test plan

• Call GET /api/v1/packages with no filters — verify statusCounts is present in the response with all equalling the sum of individual status counts
• Apply an ecosystem or name filter — verify statusCounts reflects only matching packages and all matches total
• Apply a status filter — verify statusCounts still shows counts across all statuses (not filtered by the selected status)
• Apply stale-only / bus-factor-1 / unstewareded filters — verify counts update accordingly

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Note

Medium Risk
Adds a second heavy aggregate query on every list request; counts must stay in sync with list filter logic as those evolve.

Overview
GET /api/v1/packages now returns statusCounts — stewardship tab totals (all plus each status) that respect the same non-status filters as the list (ecosystem, name, lifecycle, health band, vuln severity, stale/unstewarded/bus-factor flags) but ignore the status query param so every tab can show counts while one status is selected.

The handler loads paginated rows and counts in parallel (Promise.all) after splitting shared filter options from pagination/sort/status. The DAL adds getPackageStatusCounts with a grouped SQL query aligned to listPackagesForApi’s filter joins (stewardships, advisories, maintainers, scorecard).

Also adds .claude to backend/.prettierignore.

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