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/app/(app)/explore/page.tsx

@@ -27,9 +27,9 @@ export type RecipeResult = {
 export default async function ExplorePage({
   searchParams,
 }: {
-  searchParams: Promise<{ q?: string }>;
+  searchParams: Promise<{ q?: string; tab?: string }>;
 }) {
-  const { q } = await searchParams;
+  const { q, tab } = await searchParams;
   const sevenDaysAgo = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
 
   // Trending: public recipes ordered by favorite count in last 7 days
@@ -52,7 +52,7 @@ export default async function ExplorePage({
         gte(favorites.createdAt, sevenDaysAgo)
       )
     )
-    .where(eq(recipes.visibility, "public"))
+    .where(and(eq(recipes.visibility, "public"), eq(users.isPrivate, false)))
     .groupBy(recipes.id, users.id)
     .orderBy(desc(sql`count(${favorites.recipeId})`))
     .limit(12);
@@ -69,12 +69,19 @@ export default async function ExplorePage({
     })
     .from(recipes)
     .innerJoin(users, eq(recipes.authorId, users.id))
-    .where(eq(recipes.visibility, "public"))
+    .where(and(eq(recipes.visibility, "public"), eq(users.isPrivate, false)))
     .orderBy(desc(recipes.createdAt))
     .limit(12);
 
   const trending: RecipeResult[] = trendingRows.map(({ favoriteCount: _fc, ...r }) => r);
   const recent: RecipeResult[] = recentRows;
 
-  return <ExplorePageContent trending={trending} recent={recent} initialQuery={q ?? ""} />;
+  return (
+    <ExplorePageContent
+      trending={trending}
+      recent={recent}
+      initialQuery={q ?? ""}
+      initialTab={tab === "people" ? "people" : "recipes"}
+    />
+  );
 }