feat: private accounts, explore/people merge, meal-plan fixes, i18n and theme cleanup

- Private accounts: users.isPrivate hides a user from search and their
  recipes from search/trending/for-you discovery surfaces (follow-aware
  where the route already has session context, blanket exclusion where it
  doesn't); existing followers and direct links are unaffected, no
  follow-request approval flow was built (explicit scope limit)
- Merged /people into the Explore tab (tab=people query param); the old
  standalone route now redirects there
- "Get Ideas" vs "Surprise Me" were doing the same empty-prompt call;
  Surprise Me now injects a real random constraint (5-ingredient, one-pot,
  etc.), matching the existing pattern in the AI recipe-generate dialog
- Meal-plan day cells now link to their recipe (was dead text) and gained
  a one-click "mark as cooked" action
- Theme toggle is now a real three-way light/dark/system control instead
  of a binary flip
- Nutrition goals form had zero i18n wiring; fully localized now

New migration 0027 (users.is_private) generated, left unapplied like the
others. Verified with typecheck, lint, and a clean --no-cache docker build.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/components/settings/settings-form.tsx

@@ -7,6 +7,7 @@ import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { Textarea } from "@/components/ui/textarea";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
+import { Switch } from "@/components/ui/switch";
 import { useTranslations } from "next-intl";
 import { useLocale, SUPPORTED_LOCALES, type Locale } from "@/lib/i18n/provider";
 
@@ -17,6 +18,7 @@ type UserProps = {
   locale: string;
   bio: string | null;
   privateBio: string | null;
+  isPrivate: boolean;
 };
 
 export function SettingsForm({ user }: { user: UserProps }) {
@@ -29,6 +31,8 @@ export function SettingsForm({ user }: { user: UserProps }) {
   const [privateBio, setPrivateBio] = useState(user.privateBio ?? "");
   const [saving, setSaving] = useState(false);
   const [savingBio, setSavingBio] = useState(false);
+  const [isPrivate, setIsPrivate] = useState(user.isPrivate);
+  const [savingPrivacy, setSavingPrivacy] = useState(false);
 
   async function saveProfile() {
     setSaving(true);
@@ -65,6 +69,29 @@ export function SettingsForm({ user }: { user: UserProps }) {
 
   const bioUnchanged = bio === (user.bio ?? "") && privateBio === (user.privateBio ?? "");
 
+  async function savePrivacy(checked: boolean) {
+    setSavingPrivacy(true);
+    const previous = isPrivate;
+    setIsPrivate(checked);
+    try {
+      const res = await fetch("/api/v1/users/me", {
+        method: "PATCH",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ isPrivate: checked }),
+      });
+      if (res.ok) toast.success(t_common("saved"));
+      else {
+        setIsPrivate(previous);
+        toast.error(t_common("saveFailed"));
+      }
+    } catch {
+      setIsPrivate(previous);
+      toast.error(t_common("saveFailed"));
+    } finally {
+      setSavingPrivacy(false);
+    }
+  }
+
   return (
     <div className="space-y-6">
       <section className="rounded-xl border p-6 space-y-4">
@@ -115,6 +142,23 @@ export function SettingsForm({ user }: { user: UserProps }) {
         </Button>
       </section>
 
+      <section className="rounded-xl border p-6 space-y-1">
+        <div className="flex items-center justify-between">
+          <div>
+            <h2 className="font-semibold text-lg">{t("privateAccount")}</h2>
+            <p className="text-sm text-muted-foreground mt-1 max-w-prose">
+              {t("privateAccountDescription")}
+            </p>
+          </div>
+          <Switch
+            id="private-account"
+            checked={isPrivate}
+            disabled={savingPrivacy}
+            onCheckedChange={(checked) => { void savePrivacy(checked); }}
+          />
+        </div>
+      </section>
+
       <section className="rounded-xl border p-6 space-y-4">
         <h2 className="font-semibold text-lg">{t("language")}</h2>
         <p className="text-sm text-muted-foreground">{t("languageDescription")}</p>