feat(routing): linked complexity-boundary sliders — your own low/medium/high

The tier boundaries lived on the router and were global for every customer
of a hosted router; per-gateway tuning meant hand-editing score ranges. The
Routing page now has one track with two draggable handles (the low|medium
and medium|high boundaries) over three colored zones: handles push each
other (low can't cross medium — it shoves it along, and vice versa), the
numbers ride on the handles and the legend updates live, so nobody types
ranges by hand. Unchecked = the router's own bands, untouched behavior.

Under the hood the gateway re-maps the router's CONTINUOUS complexity score
with the user's boundaries ([routing.bands] low/medium in gateway.toml,
validated 0 < low < medium < 1) before tier chains, escalation and stats —
verified live: with bands at 0.70/0.72 a score-0.27 request that used to be
medium routed low, and back after restoring the defaults.

2 new strings in all 7 languages.

web/js/views/routing.js

@@ -71,6 +71,7 @@ export async function renderRouting() {
   const st = {
     tiers,
     taskPairs,
+    bands: routing.bands || null, // null = пороги роутера как есть
     default: routing.default || ids[0] || "",
     policy: routing.policy || { mode: "fixed_table", min_class: {} },
   };
@@ -120,6 +121,92 @@ export async function renderRouting() {
     );
   }
 
+  // Linked boundary sliders: one track, two handles (low|medium boundaries),
+  // three colored zones. Handles push each other, numbers update live —
+  // nobody types score ranges by hand.
+  function bandsCard() {
+    const DEF = { low: 0.33, medium: 0.48 };
+    const enabled = !!st.bands;
+    const b = st.bands || { ...DEF };
+    const MIN_GAP = 0.02;
+
+    const track = h("div", { class: "bands-track" });
+    const zoneLow = h("div", { class: "bands-zone z-low" });
+    const zoneMed = h("div", { class: "bands-zone z-med" });
+    const zoneHigh = h("div", { class: "bands-zone z-high" });
+    const hLow = h("div", { class: "bands-handle", tabindex: "0" }, h("span", { class: "bands-val" }));
+    const hMed = h("div", { class: "bands-handle", tabindex: "0" }, h("span", { class: "bands-val" }));
+    const legend = h("div", { class: "bands-legend" });
+    track.append(zoneLow, zoneMed, zoneHigh, hLow, hMed);
+
+    function paint() {
+      const lo = b.low, me = b.medium;
+      zoneLow.style.width = lo * 100 + "%";
+      zoneMed.style.left = lo * 100 + "%";
+      zoneMed.style.width = (me - lo) * 100 + "%";
+      zoneHigh.style.left = me * 100 + "%";
+      zoneHigh.style.width = (1 - me) * 100 + "%";
+      hLow.style.left = lo * 100 + "%";
+      hMed.style.left = me * 100 + "%";
+      hLow.querySelector(".bands-val").textContent = lo.toFixed(2);
+      hMed.querySelector(".bands-val").textContent = me.toFixed(2);
+      // подписи не наезжают, когда ручки рядом
+      hMed.querySelector(".bands-val").classList.toggle("raised", me - lo < 0.09);
+      mount(legend,
+        h("span", { class: "badge tier-low" }, `low ≤ ${lo.toFixed(2)}`),
+        h("span", { class: "badge tier-medium" }, `medium ≤ ${me.toFixed(2)}`),
+        h("span", { class: "badge tier-high" }, `high > ${me.toFixed(2)}`));
+      track.classList.toggle("disabled", !st.bands);
+    }
+
+    function drag(handle, which) {
+      handle.addEventListener("pointerdown", (e) => {
+        if (!st.bands) return;
+        handle.setPointerCapture(e.pointerId);
+        const rect = track.getBoundingClientRect();
+        const move = (ev) => {
+          let v = (ev.clientX - rect.left) / rect.width;
+          v = Math.min(0.98, Math.max(0.02, Math.round(v * 100) / 100));
+          if (which === "low") {
+            b.low = v;
+            // связанность: low толкает medium перед собой
+            if (b.medium < b.low + MIN_GAP) b.medium = Math.min(0.99, b.low + MIN_GAP);
+          } else {
+            b.medium = v;
+            // и medium толкает low назад
+            if (b.low > b.medium - MIN_GAP) b.low = Math.max(0.01, b.medium - MIN_GAP);
+          }
+          st.bands = { low: b.low, medium: b.medium };
+          paint();
+        };
+        const up = () => {
+          handle.removeEventListener("pointermove", move);
+          handle.removeEventListener("pointerup", up);
+        };
+        handle.addEventListener("pointermove", move);
+        handle.addEventListener("pointerup", up);
+      });
+    }
+    drag(hLow, "low");
+    drag(hMed, "medium");
+
+    const toggle = h("input", { type: "checkbox", checked: enabled ? "" : null });
+    toggle.checked = enabled;
+    toggle.addEventListener("change", () => {
+      st.bands = toggle.checked ? { low: b.low, medium: b.medium } : null;
+      paint();
+    });
+    paint();
+    return h(
+      "div",
+      { class: "bands-wrap" },
+      h("label", { class: "check", style: "margin-bottom:8px" }, toggle, t("routing.bands.enable")),
+      h("div", { class: "muted small", style: "margin-bottom:10px" }, t("routing.bands.hint")),
+      track,
+      legend
+    );
+  }
+
   function tierRow(tier) {
     return h(
       "div",
@@ -257,7 +344,7 @@ export async function renderRouting() {
           }
           if (Object.keys(rule).length) tasks[k] = rule;
         }
-        await api.putRouting({ tiers: st.tiers, tasks, default: st.default, policy: st.policy });
+        await api.putRouting({ tiers: st.tiers, tasks, bands: st.bands, default: st.default, policy: st.policy });
         toast(t("toast.saved"), "good");
       } catch (e) {
         toast(String(e.message || e), "bad");
@@ -282,6 +369,7 @@ export async function renderRouting() {
         "div",
         { class: "card" },
         h("div", { class: "card-head" }, h("h3", {}, t("routing.tiers")), h("span", { class: "card-head sub" }, t("routing.tierHint"))),
+        bandsCard(),
         ...Object.keys(st.tiers).map(tierRow)
       ),
       tasksCard(),