feat(cycle): second-audit feature, QoL, and wiring close

Close the second-round audit UI cluster:

- Cycle reminders: add the missing notification-event labels so the
  period-soon / period-confirm toggles read correctly on the
  notifications page, and point to them from cycle settings.
- Per-cycle history: render a recent-cycles list (range, length, period
  length, confirmed-ovulation chip) — the cycles were fetched but only
  the aggregate stats showed.
- Confirmed ovulation: carry it on the prediction DTO and surface it as a
  solid BBT-chart marker + a predictions row + a history chip.
- Log-day sheet: deselecting an enum now clears it (edits route through
  the nullable PATCH); period start/end work on any selected date for
  retroactive correction; "end period" shows only while one is open.
  Extract the payload builders as pure, unit-tested functions.
- Cycle-tracking enable toggle in account settings so any account can opt
  in before the gated page is reachable; wire the cycle data-purge button
  to the hard-delete route and document the route in the OpenAPI spec.
- Calendar legend: add the symptom dot, render fertile as a ring to match
  the grid; tighten the luteal prior bound to the engine clamp; mute the
  BBT ovulation-label colour for contrast.
- Share the cycle-start backward-walk between the wheel and the chart.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/settings/account-section.tsx

@@ -26,11 +26,7 @@ import {
   AlertDialogTitle,
   AlertDialogTrigger,
 } from "@/components/ui/alert-dialog";
-import {
-  Avatar,
-  AvatarFallback,
-  AvatarImage,
-} from "@/components/ui/avatar";
+import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar";
 import { Badge } from "@/components/ui/badge";
 import { Button } from "@/components/ui/button";
 import {
@@ -56,6 +52,7 @@ import { SettingsCardHeader } from "@/components/settings/_card-header";
 import { TimezonePicker } from "@/components/settings/timezone-picker";
 import { UnitPreferenceSelect } from "@/components/settings/unit-preference-select";
 import { InjectionSitesCard } from "@/components/settings/injection-sites-card";
+import { CycleTrackingCard } from "@/components/settings/cycle-tracking-card";
 import { detectBrowserTimezone, DEFAULT_TIMEZONE } from "@/lib/tz/format";
 
 interface PasskeyInfo {
@@ -526,7 +523,9 @@ export function AccountSection() {
               {t("settings.identity.description")}
             </p>
             <div className="space-y-2">
-              <Label htmlFor="full-name">{t("settings.identity.fullName")}</Label>
+              <Label htmlFor="full-name">
+                {t("settings.identity.fullName")}
+              </Label>
               <Input
                 id="full-name"
                 value={fullName}
@@ -538,7 +537,9 @@ export function AccountSection() {
             </div>
             <div className="grid gap-4 sm:grid-cols-2">
               <div className="space-y-2">
-                <Label htmlFor="insurer">{t("settings.identity.insurer")}</Label>
+                <Label htmlFor="insurer">
+                  {t("settings.identity.insurer")}
+                </Label>
                 <Input
                   id="insurer"
                   value={insurerName}
@@ -573,9 +574,7 @@ export function AccountSection() {
             <p
               role="alert"
               className={`text-sm ${
-                saveMsgType === "success"
-                  ? "text-success"
-                  : "text-destructive"
+                saveMsgType === "success" ? "text-success" : "text-destructive"
               }`}
             >
               {saveMsg}
@@ -601,6 +600,11 @@ export function AccountSection() {
           timezone dropdown. */}
       <InjectionSitesCard isAuthenticated={isAuthenticated} />
 
+      {/* Cycle-tracking enable on-ramp — auto-on for female accounts, but this
+          lets any account opt in (or opt out) before the gated /cycle page is
+          reachable. */}
+      <CycleTrackingCard isAuthenticated={isAuthenticated} />
+
       {/* Passkeys card */}
       <div className="bg-card border-border rounded-xl border p-6">
         <SettingsCardHeader
@@ -627,9 +631,7 @@ export function AccountSection() {
           <p
             role="alert"
             className={`mt-2 text-right text-sm ${
-              passkeyMsgType === "success"
-                ? "text-success"
-                : "text-destructive"
+              passkeyMsgType === "success" ? "text-success" : "text-destructive"
             }`}
           >
             {passkeyMsg}
@@ -1074,7 +1076,8 @@ function AvatarSection() {
       const res = await fetch("/api/user/avatar", { method: "POST", body });
       const json = await res.json().catch(() => ({}));
       if (!res.ok) {
-        if (res.status === 415) throw new Error(t("settings.avatar.invalidType"));
+        if (res.status === 415)
+          throw new Error(t("settings.avatar.invalidType"));
         if (res.status === 413) throw new Error(t("settings.avatar.tooLarge"));
         throw new Error(json.error || t("settings.avatar.error"));
       }

src/components/settings/cycle-tracking-card.tsx

@@ -0,0 +1,101 @@
+"use client";
+
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import Link from "next/link";
+import { CalendarHeart } from "lucide-react";
+
+import { Button } from "@/components/ui/button";
+import { Label } from "@/components/ui/label";
+import { Switch } from "@/components/ui/switch";
+import { SettingsCardHeader } from "@/components/settings/_card-header";
+import { useTranslations } from "@/lib/i18n/context";
+import { queryKeys } from "@/lib/query-keys";
+
+/**
+ * v1.15.0 — the cycle-tracking enable on-ramp.
+ *
+ * The cycle vertical auto-enables for accounts set to female (gender-derived
+ * default), but everyone else needs a way IN: the gated `/cycle` page bounces
+ * them home and the in-page settings (where the goal/prefs live) sit behind
+ * that same gate. This card reads the UNGATED `/api/auth/me/cycle-prefs` so any
+ * account can flip `cycleTrackingEnabled` on (or a female account can opt out)
+ * before the gated page is reachable. PATCHes the same prefs route the iOS app
+ * uses; invalidates the nav gate so the sidebar/bottom-nav entry appears.
+ */
+
+interface CyclePrefsShape {
+  cycleTrackingEnabled: boolean;
+}
+
+export function CycleTrackingCard({
+  isAuthenticated,
+}: {
+  isAuthenticated: boolean;
+}) {
+  const { t } = useTranslations();
+  const queryClient = useQueryClient();
+
+  const { data } = useQuery({
+    queryKey: queryKeys.cyclePrefs(),
+    enabled: isAuthenticated,
+    queryFn: async () => {
+      const res = await fetch("/api/auth/me/cycle-prefs");
+      if (!res.ok) throw new Error(`Request failed: ${res.status}`);
+      return (await res.json()).data as CyclePrefsShape;
+    },
+  });
+
+  const toggle = useMutation({
+    mutationFn: async (enabled: boolean) => {
+      const res = await fetch("/api/auth/me/cycle-prefs", {
+        method: "PATCH",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ enabled }),
+      });
+      if (!res.ok) throw new Error(`Request failed: ${res.status}`);
+      return (await res.json()).data as CyclePrefsShape;
+    },
+    onSuccess: () => {
+      void queryClient.invalidateQueries({ queryKey: queryKeys.cyclePrefs() });
+      void queryClient.invalidateQueries({ queryKey: queryKeys.cycle() });
+      // The nav gate reads the resolved enable state off /auth/me.
+      void queryClient.invalidateQueries({ queryKey: queryKeys.authMe() });
+    },
+  });
+
+  const enabled = data?.cycleTrackingEnabled ?? false;
+
+  return (
+    <div className="bg-card rounded-lg border p-4 sm:p-6">
+      <SettingsCardHeader
+        icon={CalendarHeart}
+        title={t("settings.cycleTracking.title")}
+        description={t("settings.cycleTracking.description")}
+      />
+      <div className="mt-4 space-y-4">
+        <div className="flex items-start justify-between gap-4">
+          <Label htmlFor="cycle-tracking-enable" className="text-sm">
+            {t("settings.cycleTracking.enable")}
+          </Label>
+          <Switch
+            id="cycle-tracking-enable"
+            checked={enabled}
+            disabled={toggle.isPending || data == null}
+            onCheckedChange={(v) => toggle.mutate(v)}
+            className="mt-0.5 shrink-0"
+          />
+        </div>
+        {enabled ? (
+          <Button variant="outline" size="sm" asChild>
+            <Link href="/cycle">{t("settings.cycleTracking.manage")}</Link>
+          </Button>
+        ) : null}
+        {toggle.isError ? (
+          <p className="text-destructive text-sm" role="alert">
+            {t("settings.cycleTracking.error")}
+          </p>
+        ) : null}
+      </div>
+    </div>
+  );
+}