feat: enhance usage analytics dashboard (#666)

- visualize input, output, and cache token segments in usage charts
- add usage period selector for 7d, 30d, 90d, and 365d
- guard usage stats against stale overlapping period requests
- normalize blank model usage into unknown buckets
- add client and server coverage for usage analytics behavior

packages/client/src/i18n/locales/de.ts

@@ -751,7 +751,7 @@ jobTriggered: 'Job ausgelost',
     estimatedCost: 'Gesch. Kosten',
     cacheHitRate: 'Cache-Trefferquote',
     modelBreakdown: 'Modellaufschluesselung',
-    dailyTrend: 'Tagliche Nutzung (letzte 30 Tage)',
+    dailyTrend: 'Tagliche Nutzung',
     date: 'Datum',
     tokens: 'Tokens',
     cache: 'Cache',

packages/client/src/i18n/locales/en.ts

@@ -973,7 +973,7 @@ export default {
     estimatedCost: 'Est. Cost',
     cacheHitRate: 'Cache Hit Rate',
     modelBreakdown: 'Model Breakdown',
-    dailyTrend: 'Daily Usage (Last 30 Days)',
+    dailyTrend: 'Daily Usage',
     date: 'Date',
     tokens: 'Tokens',
     cache: 'Cache',

packages/client/src/i18n/locales/es.ts

@@ -747,7 +747,7 @@ jobTriggered: 'Job ejecutado',
     estimatedCost: 'Costo est.',
     cacheHitRate: 'Tasa de acierto de cache',
     modelBreakdown: 'Desglose por modelo',
-    dailyTrend: 'Uso diario (ultimos 30 dias)',
+    dailyTrend: 'Uso diario',
     date: 'Fecha',
     tokens: 'Tokens',
     cache: 'Caché',

packages/client/src/i18n/locales/fr.ts

@@ -747,7 +747,7 @@ jobTriggered: 'Job declenche',
     estimatedCost: 'Cout est.',
     cacheHitRate: 'Taux de succes du cache',
     modelBreakdown: 'Repartition par modele',
-    dailyTrend: 'Utilisation quotidienne (30 derniers jours)',
+    dailyTrend: 'Utilisation quotidienne',
     date: 'Date',
     tokens: 'Jetons',
     cache: 'Cache',

packages/client/src/i18n/locales/ja.ts

@@ -747,7 +747,7 @@ export default {
     estimatedCost: '推定コスト',
     cacheHitRate: 'キャッシュヒット率',
     modelBreakdown: 'モデル別内訳',
-    dailyTrend: '日別使用量（過去30日間）',
+    dailyTrend: '日別使用量',
     date: '日付',
     tokens: 'トークン',
     cache: 'キャッシュ',

packages/client/src/i18n/locales/ko.ts

@@ -747,7 +747,7 @@ export default {
     estimatedCost: '예상 비용',
     cacheHitRate: '캐시 적중률',
     modelBreakdown: '모델별 분포',
-    dailyTrend: '일별 사용량 (최근 30일)',
+    dailyTrend: '일별 사용량',
     date: '날짜',
     tokens: '토큰',
     cache: '캐시',

packages/client/src/i18n/locales/pt.ts

@@ -747,7 +747,7 @@ jobTriggered: 'Job acionado',
     estimatedCost: 'Custo est.',
     cacheHitRate: 'Taxa de acerto de cache',
     modelBreakdown: 'Detalhamento por modelo',
-    dailyTrend: 'Uso diario (ultimos 30 dias)',
+    dailyTrend: 'Uso diario',
     date: 'Data',
     tokens: 'Tokens',
     cache: 'Cache',

packages/client/src/i18n/locales/zh-TW.ts

@@ -975,7 +975,7 @@ export default {
     estimatedCost: '預估費用',
     cacheHitRate: '快取命中率',
     modelBreakdown: '模型分布',
-    dailyTrend: '每日用量（近 30 天）',
+    dailyTrend: '每日用量',
     date: '日期',
     tokens: 'Token',
     cache: '快取',

packages/client/src/i18n/locales/zh.ts

@@ -975,7 +975,7 @@ export default {
     estimatedCost: '预估费用',
     cacheHitRate: '缓存命中率',
     modelBreakdown: '模型分布',
-    dailyTrend: '每日用量（近 30 天）',
+    dailyTrend: '每日用量',
     date: '日期',
     tokens: 'Token',
     cache: '缓存',