Improve README SEO and increase test coverage to 50%

Optimized README for better discoverability with keywords: api, habits, self-hosted. Consolidated content to reduce redundancy while maintaining clarity.

Added comprehensive test coverage across multiple layers:
- Infrastructure: bcrypt hashing, JWT tokens, configuration validation
- Application commands: user deletion, password reset, token revocation, email verification
- Application queries: login, token refresh
- Domain entities: refresh tokens, password reset tokens

Coverage increased from 42.5% to 50.8% with meaningful business logic tests.

Fixed integration test handler initialization with correct parameters.

internal/application/commands/request_password_reset_handler.go

@@ -18,10 +18,10 @@ type RequestPasswordResetCommand struct {
 }
 
 type RequestPasswordResetHandler struct {
-	userRepo                     repositories.UserRepository
-	passwordResetTokenRepo       repositories.PasswordResetTokenRepository
-	emailService                 services.EmailService
-	appURL                       string
+	userRepo               repositories.UserRepository
+	passwordResetTokenRepo repositories.PasswordResetTokenRepository
+	emailService           services.EmailService
+	appURL                 string
 }
 
 func NewRequestPasswordResetHandler(