fix: resolve user emails in Knowledge UI and audit chart timescale

[cjimti]

Summary

Three bugs in the Admin portal:

• Knowledge > Insights tab: "Captured By" column displayed raw UUIDs instead of user email addresses. Same for "Reviewed By" and "Applied By" in the insight detail drawer.
• Knowledge > Changesets tab: "Applied By" column displayed raw UUIDs. Same for "Approved By", "Applied By", and "Rolled Back By" in the changeset detail drawer.
• Audit > Overview tab: Activity chart X-axis labels didn't adapt to the selected time range (always showed HH:MM regardless of 1h/6h/24h/7d selection).

Changes

Knowledge user email resolution (KnowledgePage.tsx)

The audit filters endpoint already returns user_labels: Record<string, string> mapping user IDs to emails, and formatUser(id, email?) already handles display. The Knowledge page simply wasn't consuming this data.

• Added useAuditFilters() hook call in both InsightsTab and ChangesetsTab
• Updated all 8 formatUser(id) calls to formatUser(id, userLabels[id]):
  • InsightsTab table row (captured_by)
  • InsightDrawer metadata (captured_by), lifecycle (reviewed_by, applied_by)
  • ChangesetsTab table row (applied_by)
  • ChangesetDrawer metadata (approved_by, applied_by), rollback (rolled_back_by)
• Passed userLabels as a prop from tab components into drawer components

Audit chart timescale (AuditLogPage.tsx)

The TimeseriesChart component already accepts an optional preset prop that controls X-axis label formatting (HH:MM for 1h/6h, hour-only for 24h, Mon DD for 7d). The OverviewTab had preset from useTimeRangeStore() but wasn't passing it through.

• Added preset={preset} to the TimeseriesChart invocation (one-line fix)

Dependency bump (go.mod, go.sum, test)

• Bumped mcp-datahub v0.8.0 → v0.8.1 (fixes Query mutation schema for flat subjects array)
• Aligned datahub_client_writer_test.go mock response with the new response format

Test plan

• npm run build in admin-ui/ — no TypeScript errors
• make verify — full CI suite passes (fmt, test, lint, security, coverage, mutation, release-check)
• Open Admin UI → Knowledge → Insights tab: "Captured By" shows email addresses instead of UUIDs
• Click an insight row → drawer shows email for "Captured By", "Reviewed By", "Applied By"
• Knowledge → Changesets tab: "Applied By" shows email addresses
• Click a changeset row → drawer shows email for "Approved By", "Applied By", "Rolled Back By"
• Audit → Overview tab: switch between 1h/6h/24h/7d and verify X-axis labels adapt (HH:MM → hour → Mon DD)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.65%. Comparing base (4dded54) to head (138b197).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #147   +/-   ##
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  Coverage   90.65%   90.65%           
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  Files         113      113           
  Lines       11032    11032           
=======================================
  Hits        10001    10001           
  Misses        743      743           
  Partials      288      288           

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