Metric charts lose tiny-value precision and collapse date-like category labels #1272

Metric charts can collapse finite small values and make distinct categorical labels ambiguous.

Reproduced in the selected @codefly-dev/ui 0.12.2-c3221289 package, also present in owner source df044ce:

• niceTicks(0, 2e-12) returns [0,0,0,0,0] because metric-geometry.ts rounds ticks with toFixed(10). A chart containing 1e-12 and 2e-12 loses its scale. The public ChartSeries contract supplies no minimum finite magnitude.
• The default metric-chart Intl.NumberFormat renders 0.0001 and 0.0002 both as 0 in tooltips/accessibility tables. Consumers can use the existing formatValue extension; geometry still needs an owner fix.
• Categorical keys 2025-01-01 and 2026-01-01 both display as Jan 1 in axes and hover titles because formatAxisKey infers date formatting and omits the year. The raw accessible table preserves them, but the visual labels are ambiguous. An existing/public label-format option, if available, should be documented for this consumer; otherwise preserve distinction in owner formatting.

Found while reviewing Robin's execution chart preview. Robin uses formatValue={String} and temporarily refuses extremely small nonzero values and date-shaped categories, with raw output still available in Details. It does not duplicate chart geometry. That restriction is a stopgap, not a fix for the shared renderer.

Searched current issues/PRs; the metric-tier/layout work does not change these chart files. Please cover tiny finite domains and distinct date-like categorical labels with regression tests at the owner.