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.Domain/Entities/VerificationCode.cs

@@ -0,0 +1,12 @@
+namespace HealthManager.Domain.Entities;
+
+public class VerificationCode
+{
+    public Guid Id { get; set; } = Guid.NewGuid();
+    public string Phone { get; set; } = string.Empty;
+    public string Code { get; set; } = string.Empty;
+    public string Type { get; set; } = "login";
+    public DateTime ExpiresAt { get; set; }
+    public bool IsUsed { get; set; }
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+}