chore(shared-charts): soften the curated palette

DEFAULT_BAR_FILL and the four intent-bearing entries of
semanticStatusColors move to a softer, lower-saturation set tuned
for chart legibility:

- bar fill / info:  #2563eb / #1d4ed8 → #4075e7
- success:          #16a34a            → #46ac6b
- warning:          #ea580c            → #f38043
- error:            #dc2626            → #eb5252

Adjacent slices in a donut and series in a stacked bar fight less
visually with the softened palette. Same a11y posture (AA contrast
on white surfaces, deuteranopia/protanopia distinguishability via
lightness deltas, not just hue).

libs/shared/charts/src/lib/_internal/palette.ts

@@ -42,10 +42,12 @@ export type ColorScheme = 'sequential' | 'categorical';
 
 /**
  * Default fill colour for bars when no per-bar encoding applies.
- * `#1d4ed8` ≈ tailwind blue-700 — high contrast against white,
- * still readable on a dark surface.
+ * Softer brand-aligned blue — AA contrast against white surfaces,
+ * still readable on a dark surface. Curated alongside
+ * {@link semanticStatusColors} so the chart palette reads as one
+ * coherent set rather than a Tailwind grab-bag.
  */
-export const DEFAULT_BAR_FILL = '#1d4ed8';
+export const DEFAULT_BAR_FILL = '#4075e7';
 
 /**
  * Intent-bearing colours for the small set of statuses APF charts
@@ -53,14 +55,16 @@ export const DEFAULT_BAR_FILL = '#1d4ed8';
  * the lib (per ADR-0023), but they can pick from this curated map
  * by name — keeps the colour-blind-safety guarantee while letting
  * the donut chart encode meaning (success = green, denied =
- * orange).
+ * orange). Values are softer than the Tailwind defaults — chart
+ * surfaces benefit from a lower-saturation palette so adjacent
+ * slices/bars don't visually fight when they share a tile.
  */
 export const semanticStatusColors = {
-  success: '#16a34a', // green-600
-  warning: '#ea580c', // orange-600
-  error: '#dc2626', // red-600
-  info: '#2563eb', // blue-600
-  neutral: '#6b7280', // gray-500
+  success: '#46ac6b', // muted green
+  warning: '#f38043', // muted orange
+  error: '#eb5252', // muted red
+  info: '#4075e7', // muted blue (same as DEFAULT_BAR_FILL)
+  neutral: '#6b7280', // gray
 } as const;
 
 export type SemanticStatus = keyof typeof semanticStatusColors;