feat: replace Redis with PostgreSQL for caching, rate limiting, SMS codes, and token blacklist

- Add 4 PG entities: VerificationCode, RateLimitEntry, TokenBlacklistEntry, CacheEntry
- Add 4 services: VerificationService, RateLimitService, TokenBlacklistService, CacheService
- Add CleanupBackgroundService for periodic expired data cleanup
- Add MigrationHelper for safe schema migration without data loss
- Update AuthController: real SMS code generation, rate limiting, logout endpoint with JWT blacklist
- Update JwtProvider: add JTI claim for token revocation
- Update Program.cs: register new services, JWT blacklist validation, DB migration
- Remove StackExchange.Redis NuGet package and all Redis config references
- Update start-dev.bat: 6→5 services, remove Redis startup
- Update docs: remove Redis references from all documentation
- Fix: logout button spacing on profile page
- Fix: .gitignore data/→/data/ to not ignore Infrastructure/Data/

backend/src/HealthManager.WebApi/Services/CleanupBackgroundService.cs

@@ -0,0 +1,31 @@
+using HealthManager.Application.Services;
+using Microsoft.EntityFrameworkCore;
+
+namespace HealthManager.WebApi.Services;
+
+public class CleanupBackgroundService(
+    IServiceScopeFactory scopeFactory) : BackgroundService
+{
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try
+            {
+                using var scope = scopeFactory.CreateScope();
+                var verification = scope.ServiceProvider.GetRequiredService<VerificationService>();
+                var tokenBlacklist = scope.ServiceProvider.GetRequiredService<TokenBlacklistService>();
+
+                await verification.CleanupExpiredAsync();
+                await tokenBlacklist.CleanupExpiredAsync();
+
+                var db = scope.ServiceProvider.GetRequiredService<Infrastructure.Data.AppDbContext>();
+                await db.RateLimitEntries.Where(r => r.ExpiresAt < DateTime.UtcNow).ExecuteDeleteAsync(stoppingToken);
+                await db.CacheEntries.Where(c => c.ExpiresAt < DateTime.UtcNow).ExecuteDeleteAsync(stoppingToken);
+            }
+            catch { /* skip cleanup errors */ }
+
+            await Task.Delay(TimeSpan.FromMinutes(5), stoppingToken);
+        }
+    }
+}