feat(usage): redesign Usage Analytics with accurate token averages

- Fix token averaging: calculate over active hours/days only (not full period)
- Enable hourlyData query for all time ranges (not just 24h)
- Rename 'Usage Forecast' to 'Usage Averages' (real data, not projections)
- Add avg/request metric and active hours/days context
- Update terminology: Input/Output Tokens with info tooltips
- Add Estimated Cost stat card with per-model calculation
- Add quota warning alert banner when models exceed 80%
- Add ModelQuotaBar component with color thresholds

src/lib/nivo-theme.ts

@@ -31,7 +31,7 @@ export const nivoTheme: PartialTheme = {
     },
     legend: {
       text: {
-        fontFamily: "Inter, sans-serif",
+        fontFamily: 'Inter, sans-serif',
         fontSize: 11,
         fill: '#6b7280',
       },
@@ -45,7 +45,7 @@ export const nivoTheme: PartialTheme = {
   },
   legends: {
     text: {
-      fontFamily: "Inter, sans-serif",
+      fontFamily: 'Inter, sans-serif',
       fontSize: 11,
       fill: '#6b7280',
     },
@@ -54,7 +54,7 @@ export const nivoTheme: PartialTheme = {
     container: {
       background: '#16161e',
       color: '#e8eaed',
-      fontFamily: "Inter, sans-serif",
+      fontFamily: 'Inter, sans-serif',
       fontSize: 12,
       borderRadius: 8,
       border: '1px solid rgba(255,255,255,0.06)',