feat: complete mealplanner app (backend + frontend + deployment)

.NET 8 backend with Zitadel JWT auth, TheMealDB integration,
weekly meal plan generation, shopping list aggregation.
Vue 3 + Tailwind 4 frontend with dark emerald theme,
manual OIDC PKCE auth, all views implemented.
Multi-stage Dockerfile with nginx reverse proxy.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/Controllers/SettingsController.cs

@@ -0,0 +1,42 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using MealPlanner.Data;
+using MealPlanner.Models;
+
+namespace MealPlanner.Controllers;
+
+[ApiController]
+[Route("api/settings")]
+[Authorize]
+public class SettingsController(AppDbContext db) : ControllerBase
+{
+    private string UserId => User.FindFirst("sub")?.Value ?? throw new UnauthorizedAccessException();
+
+    [HttpGet]
+    public async Task<IActionResult> Get()
+    {
+        var settings = await db.UserSettings.FindAsync(UserId);
+        if (settings is null)
+        {
+            settings = new UserSettings { UserId = UserId, HouseholdSize = 2 };
+            db.UserSettings.Add(settings);
+            await db.SaveChangesAsync();
+        }
+        return Ok(settings);
+    }
+
+    [HttpPut]
+    public async Task<IActionResult> Update([FromBody] UserSettings updated)
+    {
+        var settings = await db.UserSettings.FindAsync(UserId);
+        if (settings is null)
+        {
+            settings = new UserSettings { UserId = UserId };
+            db.UserSettings.Add(settings);
+        }
+
+        settings.HouseholdSize = updated.HouseholdSize;
+        await db.SaveChangesAsync();
+        return Ok(settings);
+    }
+}