feat(sessions): merge the activity feed into a tab on /sessions

Sessions and Activity Feed are two views of the same event pipeline, so
they now share one page: /sessions renders a tab bar (Sessions | Activity
Feed) with the active view in the ?view= query param, and /activity
redirects to /sessions?view=events. The sidebar entry is dropped.

The tab bar itself moves out of SettingsHub into components/PageTabs so
both hubs share it, and DocumentTitle loses the two branches for paths
that now only redirect.

client/src/pages/SettingsHub.tsx

@@ -7,6 +7,7 @@ import type { ComponentType } from "react";
 import { useSearchParams } from "react-router-dom";
 import { useTranslation } from "react-i18next";
 import { Boxes, Settings as SettingsIcon, SquareTerminal, MousePointerClick } from "lucide-react";
+import { PageTabs } from "../components/PageTabs";
 import { Settings } from "./Settings";
 import { CcConfig } from "./CcConfig";
 
@@ -45,37 +46,17 @@ export function SettingsHub() {
 
   return (
     <div className="space-y-6">
-      <div
-        role="tablist"
-        aria-label={t("tools.label", "Tools")}
-        className="flex items-center gap-1.5 overflow-x-auto no-scrollbar border-b border-border/60 pb-2"
-      >
-        {TOOL_TABS.map(({ id, labelKey, Icon, Panel }) => {
-          const isActive = id === active.id;
-          return (
-            <button
-              key={id}
-              type="button"
-              role="tab"
-              aria-selected={isActive}
-              onClick={() =>
-                setParams(id === DASHBOARD_TAB.id ? {} : { tool: id }, { replace: true })
-              }
-              className={`inline-flex items-center gap-1.5 text-xs whitespace-nowrap px-3 py-1.5 rounded-lg border transition-colors flex-shrink-0 ${
-                isActive
-                  ? "bg-accent/15 border-accent/30 text-accent"
-                  : "border-border text-fg-secondary hover:text-fg-primary hover:bg-surface-3"
-              }`}
-            >
-              <Icon className="w-3.5 h-3.5" />
-              {t(labelKey)}
-              {!Panel && (
-                <span className="text-[10px] text-fg-muted">{t("tools.soonBadge", "soon")}</span>
-              )}
-            </button>
-          );
-        })}
-      </div>
+      <PageTabs
+        ariaLabel={t("tools.label", "Tools")}
+        activeId={active.id}
+        onSelect={(id) => setParams(id === DASHBOARD_TAB.id ? {} : { tool: id }, { replace: true })}
+        tabs={TOOL_TABS.map(({ id, labelKey, Icon, Panel }) => ({
+          id,
+          Icon,
+          label: t(labelKey),
+          ...(Panel ? {} : { badge: t("tools.soonBadge", "soon") }),
+        }))}
+      />
 
       {active.Panel ? (
         <active.Panel />