feat(dashboard): windowed stats per range + clear-logs button

- Stats snapshot now computes the KPI totals AND the breakdown from the
  in-window per-minute buckets (previously they used all-time accumulators, so
  switching 1h/24h/7d changed only the chart, not the numbers). Buckets now
  carry failovers + per-group breakdown; Prometheus keeps all-time counters.
- New DELETE /admin/api/stats clears all in-memory stats and truncates the
  JSONL log; the dashboard gets a "Clear logs" button (with confirm).

web/js/api.js

@@ -87,6 +87,7 @@ export const api = {
 
   // stats
   stats: (range, groupby) => j("GET", `/stats?range=${range}&groupby=${groupby}`),
+  clearStats: () => j("DELETE", "/stats"),
   requests: (limit = 50, offset = 0) => j("GET", `/requests?limit=${limit}&offset=${offset}`),
 
   // playground

web/js/i18n/en.js

@@ -59,6 +59,9 @@ export default {
   // dashboard
   "dash.title": "Dashboard",
   "dash.subtitle": "Live traffic, cost and routing analytics for your model pool.",
+  "dash.clear": "Clear logs",
+  "dash.clearConfirm": "Clear all recorded stats and logs? This cannot be undone.",
+  "dash.cleared": "Logs cleared",
   "dash.range": "Range",
   "dash.range.1h": "1h",
   "dash.range.24h": "24h",

web/js/i18n/ru.js

@@ -58,6 +58,9 @@ export default {
   // dashboard
   "dash.title": "Дашборд",
   "dash.subtitle": "Трафик в реальном времени, расходы и аналитика роутинга по пулу моделей.",
+  "dash.clear": "Очистить логи",
+  "dash.clearConfirm": "Очистить всю статистику и логи? Отменить нельзя.",
+  "dash.cleared": "Логи очищены",
   "dash.range": "Период",
   "dash.range.1h": "1ч",
   "dash.range.24h": "24ч",

web/js/views/dashboard.js

@@ -1,5 +1,5 @@
 // Dashboard — KPIs, time-series charts, breakdown, recent requests, health.
-import { h, mount, money, num, ms, pct, timeAgo } from "../ui.js";
+import { h, mount, money, num, ms, pct, timeAgo, toast, confirmDialog } from "../ui.js";
 import { t } from "../i18n.js";
 import { api } from "../api.js";
 import { lineChart, barList } from "../charts.js";
@@ -53,10 +53,24 @@ export async function renderDashboard() {
           "div",
           { class: "flex" },
           h("div", { class: "grow" }, h("h2", {}, t("dash.title")), h("p", {}, t("dash.subtitle"))),
-          seg(RANGES, range, (r) => {
-            range = r;
-            load();
-          }, (r) => t("dash.range." + r))
+          h("div", { class: "flex", style: "gap:8px;align-items:center" },
+            seg(RANGES, range, (r) => {
+              range = r;
+              load();
+            }, (r) => t("dash.range." + r)),
+            h("button", {
+              class: "btn sm danger",
+              onClick: async () => {
+                if (!(await confirmDialog(t("dash.clearConfirm")))) return;
+                try {
+                  await api.clearStats();
+                  toast(t("dash.cleared"), "good");
+                  await load();
+                } catch (e) {
+                  toast(String(e.message || e), "bad");
+                }
+              },
+            }, t("dash.clear")))
         )
       ),