feat(analytics): add previous-period KPI delta comparisons

[romahawk]

Summary

• Add KPI deltas versus previous period for Accuracy, Volume, and Best Zone.
• Compute previous period as a strict non-overlapping window before current selected dates.
• Prevent misleading comparisons when previous period has no baseline data.

Changes

• src/pages/Dashboard.jsx
  • derive previous period date range and previous filtered sessions
  • compute previousKpis
• src/pages/dashboard/AnalyticsSection.jsx
  • pass previousKpis to KPI tiles
• src/components/KpiTiles.jsx
  • render compact �s prev deltas with tone/color
  • show �s prev n/a when previous baseline is empty

Validation

• npm run lint
• npm run build
• Visual: switch period/date ranges and verify KPI delta lines update or show
  /a when no previous data

[vercel]

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Project	Deployment	Actions	Updated (UTC)
smartshooter	Ready	Preview, Comment	Feb 15, 2026 6:48pm