Let chart views avoid the dashboard utility bulk

The intraday chart data builder lived inside dashboard-utils with observation-source and TAF helpers, so chart consumers had to depend on the large dashboard utility surface. This moves chart data preparation, observation-source helpers, and TAF marker labels into focused modules while keeping dashboard-utils re-export compatibility.

Constraint: Preserve existing chart data shape, observation labels, TAF labels, and legacy dashboard-utils exports.

Rejected: Rewrite chart data generation while moving it | this pass is a boundary move only so visual behavior remains stable.

Confidence: high

Scope-risk: moderate

Reversibility: clean

Tested: TypeScript diagnostics for chart-utils, dashboard-utils, observation-source-utils, and taf-utils

Tested: npm run build

Not-tested: Browser visual regression across every chart city.

frontend/components/dashboard/DetailPanel.tsx

@@ -12,10 +12,10 @@ import { getOfficialSourceLinks } from "@/lib/dashboard-official-sources";
 import { CityDetail } from "@/lib/dashboard-types";
 import { trackAppEvent } from "@/lib/app-analytics";
 import { getTodayPolymarketUrl } from "@/lib/polymarket-market-links";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 import {
   getCityProfileStats,
   getRiskBadgeLabel,
-  getTemperatureChartData,
 } from "@/lib/dashboard-utils";
 import { normalizeObservationSourceLabel } from "@/lib/source-labels";
 

frontend/components/dashboard/FutureForecastModal.tsx

@@ -23,11 +23,11 @@ import {
   ModelForecast,
   ProbabilityDistribution,
 } from "@/components/dashboard/PanelSections";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 import {
   getFutureModalView,
   getModelView,
   getProbabilityView,
-  getTemperatureChartData,
   getWeatherSummary,
 } from "@/lib/dashboard-utils";
 import { getTodayPaceView } from "@/lib/pace-utils";

frontend/components/dashboard/PanelSections.tsx

@@ -12,12 +12,12 @@ import {
   MarketTopBucket,
   ProbabilityBucket,
 } from "@/lib/dashboard-types";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 import {
   getHeroMetaItems,
   getModelView,
   getProbabilityView,
   getRiskBadgeLabel,
-  getTemperatureChartData,
   getWeatherSummary,
 } from "@/lib/dashboard-utils";
 import {

frontend/components/dashboard/scan-terminal/AiCityTemperatureChart.tsx

@@ -4,7 +4,7 @@ import { BarChart3 } from "lucide-react";
 import type { CityDetail } from "@/lib/dashboard-types";
 import { useChart } from "@/hooks/useChart";
 import { useI18n } from "@/hooks/useI18n";
-import { getTemperatureChartData } from "@/lib/dashboard-utils";
+import { getTemperatureChartData } from "@/lib/chart-utils";
 
 type TemperatureChartData = NonNullable<ReturnType<typeof getTemperatureChartData>>;