feat(panel): customisable dashboard with registrable widgets (spec 0058)

[glennjacobs]

Implements the panel dashboard from spec 0058 — a per-staff customisable dashboard for the Inertia panel, with a widget extension point add-ons can plug into, nine first-party widgets over real data, and a brand-anchored chart palette.

What's included

Widget extension point

• Widget abstract + WidgetRegistry, registered via Section::widgets() or Panel::widget(), ordered through the shared OrderResolver and permission-filtered.
• Each visible widget's data(DashboardRange) ships as a deferred Inertia prop in its own group, so widgets load in parallel behind skeletons; a slow add-on widget never blocks the rest, and hidden widgets compute nothing.
• The grid owns the card chrome (drag handle, hide, header) — widget components render body only, so add-on widgets get reorder/hide/permission behaviour for free.

Per-staff layout

• New panel-owned staff_preferences table (generic per-staff key/value). Merge-on-read reconciles the stored layout with the live registry (uninstalled keys drop, new widgets append with defaults).
• PUT/DELETE panel/dashboard/preferences; customise mode with drag-reorder, hide, an "Add a widget" dialog, and reset-to-defaults. Range + layout persist on every change.

Nine first-party widgets — KPIs (deltas + sparklines), revenue-over-time, recent orders, top products, sales by channel, new-vs-returning, customer-group split, low stock, tasks. Revenue is valued in the default currency via the exchange rate captured at placement (the spec-0050 basis); figures aggregate in SQL.

Charts & brand colours

• New --color-chart-* theme tokens anchored on the Lunar icon blue, dataviz-validated in light and dark. TimeSeriesChart recoloured off sage.
• New public Sparkline and DonutChart components (dependency-free SVG), exported via ui.ts / @lunarphp/panel.
• Large summary totals abbreviate (£1.4M) in tight readouts via OrderMetrics::formatCompact(), with the exact value preserved in tooltips and donut legends.

Add-on surface — the example add-on gains a CustomerCountWidget; extension docs (TMP-DOCS.md, example README) updated. Translations across all 16 locales.

Design decisions

• Per-staff, server-side layout (not global, not localStorage): permission filtering already personalises the widget set, roles want different landing pages, and it follows staff across devices. A store-curated default layout is noted as a follow-on.
• Server-side money formatting kept throughout (including compaction), consistent with the panel convention. Compact k/M/B suffixes are en-centric via lang keys (ICU has no compact-currency mode); locale-perfect compaction is a documented follow-on.

Testing

• Panel Pest suite: 722 passing — registry ordering/permissions, preference merge/validation/isolation, per-widget data correctness (currency conversion, deltas, buckets), deferred-prop assertions, compaction, and add-on widget registration (fixture + example add-on).
• Frontend: 231 vitest (charts, widget card drag/hide, tooltip props), type-check, npm run build + add-on build.
• PHPStan and Pint clean.
• Verified end-to-end in the running panel: all widgets render with demo data, range switch + customise-mode changes persist correctly.

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