feat: per-key spend accounting and per-task complexity pinning

API keys page: the table now answers "which department spends what" — per-key
requests, tokens in/out and cost for a selectable window (24h/7d/30d) plus a
cumulative all-time cost column, joined from stats by the key's account.

The stats log stays bounded while the accounting survives: once stats.jsonl
exceeds max_file_mb (default 16, 0 disables), records older than the
retention window fold into cumulative per-account totals in a small sidecar
file (tmp+rename on both) and leave the log. alltime = folded + in-file, a
record is never counted twice, verified end-to-end on synthetic data
(1.2 MB → 301 KB, totals identical before/after compaction and restarts).

Routing: a task rule can now PIN the complexity tier —
`[routing.tasks.legal] models=[...] tier="high"` (old plain-array rules parse
unchanged). The pinned tier replaces the router's verdict before the
escalation check and reports itself as route_source "router+task-rule@high".
The Routing page grows a per-task «Complexity» selector (Auto/low/medium/
high); verified live: a code prompt with a pinned high went
router+task-rule@high → the expensive model.

13 new strings in all 7 languages; docs/ROUTING(.ru) updated.

web/js/i18n/de.js

@@ -621,4 +621,10 @@ export default {
   "bm.cutByCap": "Budget ging fürs Denken drauf — keine Antwort mehr",
   "shell.uiStale": "Das Gateway wurde aktualisiert — diese Seite zeigt eine ältere Oberfläche.",
   "shell.reload": "Neu laden",
+  "keys.col.requests": "Anfragen",
+  "keys.col.tokens": "Tokens ein/aus",
+  "keys.col.costAll": "$ gesamt",
+  "routing.tasks.tier": "Komplexität",
+  "routing.tasks.tierAuto": "Auto (Router)",
+  "routing.tasks.tierHint": "Komplexität für diese Aufgabe festlegen: das Router-Urteil wird ersetzt, high eskaliert weiterhin über die Modellliste.",
 };

web/js/i18n/en.js

@@ -614,4 +614,10 @@ export default {
   "bm.cutByCap": "budget spent on reasoning — answer never came",
   "shell.uiStale": "The gateway was updated — this page is running an older interface.",
   "shell.reload": "Reload",
+  "keys.col.requests": "Requests",
+  "keys.col.tokens": "Tokens in/out",
+  "keys.col.costAll": "$ all-time",
+  "routing.tasks.tier": "Complexity",
+  "routing.tasks.tierAuto": "Auto (router)",
+  "routing.tasks.tierHint": "Pin the complexity tier for this task: the router's verdict is replaced, high still escalates over the model list.",
 };

web/js/i18n/es.js

@@ -621,4 +621,10 @@ export default {
   "bm.cutByCap": "presupuesto gastado en razonar — sin respuesta final",
   "shell.uiStale": "La pasarela se actualizó — esta página usa una interfaz antigua.",
   "shell.reload": "Recargar",
+  "keys.col.requests": "Peticiones",
+  "keys.col.tokens": "Tokens ent/sal",
+  "keys.col.costAll": "$ total",
+  "routing.tasks.tier": "Complejidad",
+  "routing.tasks.tierAuto": "Auto (router)",
+  "routing.tasks.tierHint": "Fijar la complejidad de esta tarea: el veredicto del router se sustituye, high sigue escalando por encima de la lista de modelos.",
 };

web/js/i18n/fr.js

@@ -621,4 +621,10 @@ export default {
   "bm.cutByCap": "budget épuisé en raisonnement — pas de réponse",
   "shell.uiStale": "La passerelle a été mise à jour — cette page utilise une ancienne interface.",
   "shell.reload": "Recharger",
+  "keys.col.requests": "Requêtes",
+  "keys.col.tokens": "Tokens in/out",
+  "keys.col.costAll": "$ au total",
+  "routing.tasks.tier": "Complexité",
+  "routing.tasks.tierAuto": "Auto (routeur)",
+  "routing.tasks.tierHint": "Fixer la complexité de cette tâche : le verdict du routeur est remplacé, high continue d'escalader au-dessus de la liste de modèles.",
 };

web/js/i18n/ru.js

@@ -613,4 +613,10 @@ export default {
   "bm.cutByCap": "бюджет ушёл на размышления — ответ не успел",
   "shell.uiStale": "Шлюз обновился — на этой странице старый интерфейс.",
   "shell.reload": "Перезагрузить",
+  "keys.col.requests": "Запросы",
+  "keys.col.tokens": "Токены вх/исх",
+  "keys.col.costAll": "$ за всё время",
+  "routing.tasks.tier": "Сложность",
+  "routing.tasks.tierAuto": "Авто (по роутеру)",
+  "routing.tasks.tierHint": "Закрепить уровень сложности для задачи: вердикт роутера заменяется, high по-прежнему эскалирует поверх списка моделей.",
 };

web/js/i18n/tr.js

@@ -621,4 +621,10 @@ export default {
   "bm.cutByCap": "bütçe düşünmeye gitti — yanıt gelemedi",
   "shell.uiStale": "Ağ geçidi güncellendi — bu sayfa eski arayüzü çalıştırıyor.",
   "shell.reload": "Yeniden yükle",
+  "keys.col.requests": "İstekler",
+  "keys.col.tokens": "Token giriş/çıkış",
+  "keys.col.costAll": "$ toplam",
+  "routing.tasks.tier": "Karmaşıklık",
+  "routing.tasks.tierAuto": "Otomatik (yönlendirici)",
+  "routing.tasks.tierHint": "Bu görev için karmaşıklık katmanını sabitle: yönlendiricinin kararı değiştirilir, high yine model listesinin üzerine tırmanır.",
 };

web/js/i18n/zh.js

@@ -621,4 +621,10 @@ export default {
   "bm.cutByCap": "预算全用于思考——未能给出答案",
   "shell.uiStale": "网关已更新 — 此页面运行的是旧界面。",
   "shell.reload": "重新加载",
+  "keys.col.requests": "请求数",
+  "keys.col.tokens": "Token 入/出",
+  "keys.col.costAll": "$ 累计",
+  "routing.tasks.tier": "复杂度",
+  "routing.tasks.tierAuto": "自动（路由器）",
+  "routing.tasks.tierHint": "为该任务固定复杂度层级：替换路由器的判断，high 仍会越过模型列表进行升级。",
 };