Migrate from Gin to Echo framework and add comprehensive integration tests

Major changes:
- Migrate all handlers from Gin to Echo framework
- Add new apperrors, echohelpers, and validator packages
- Update middleware for Echo compatibility
- Add ArchivedHandler to task categorization chain (archived tasks go to cancelled_tasks column)
- Add 6 new integration tests:
  - RecurringTaskLifecycle: NextDueDate advancement for weekly/monthly tasks
  - MultiUserSharing: Complex sharing with user removal
  - TaskStateTransitions: All state transitions and kanban column changes
  - DateBoundaryEdgeCases: Threshold boundary testing
  - CascadeOperations: Residence deletion cascade effects
  - MultiUserOperations: Shared residence collaboration
- Add single-purpose repository functions for kanban columns (GetOverdueTasks, GetDueSoonTasks, etc.)
- Fix RemoveUser route param mismatch (userId -> user_id)
- Fix determineExpectedColumn helper to correctly prioritize in_progress over overdue

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/dto/requests/auth.go

@@ -2,47 +2,47 @@ package requests
 
 // LoginRequest represents the login request body
 type LoginRequest struct {
-	Username string `json:"username" binding:"required_without=Email"`
-	Email    string `json:"email" binding:"required_without=Username,omitempty,email"`
-	Password string `json:"password" binding:"required,min=1"`
+	Username string `json:"username" validate:"required_without=Email"`
+	Email    string `json:"email" validate:"required_without=Username,omitempty,email"`
+	Password string `json:"password" validate:"required,min=1"`
 }
 
 // RegisterRequest represents the registration request body
 type RegisterRequest struct {
-	Username  string `json:"username" binding:"required,min=3,max=150"`
-	Email     string `json:"email" binding:"required,email,max=254"`
-	Password  string `json:"password" binding:"required,min=8"`
-	FirstName string `json:"first_name" binding:"max=150"`
-	LastName  string `json:"last_name" binding:"max=150"`
+	Username  string `json:"username" validate:"required,min=3,max=150"`
+	Email     string `json:"email" validate:"required,email,max=254"`
+	Password  string `json:"password" validate:"required,min=8"`
+	FirstName string `json:"first_name" validate:"max=150"`
+	LastName  string `json:"last_name" validate:"max=150"`
 }
 
 // VerifyEmailRequest represents the email verification request body
 type VerifyEmailRequest struct {
-	Code string `json:"code" binding:"required,len=6"`
+	Code string `json:"code" validate:"required,len=6"`
 }
 
 // ForgotPasswordRequest represents the forgot password request body
 type ForgotPasswordRequest struct {
-	Email string `json:"email" binding:"required,email"`
+	Email string `json:"email" validate:"required,email"`
 }
 
 // VerifyResetCodeRequest represents the verify reset code request body
 type VerifyResetCodeRequest struct {
-	Email string `json:"email" binding:"required,email"`
-	Code  string `json:"code" binding:"required,len=6"`
+	Email string `json:"email" validate:"required,email"`
+	Code  string `json:"code" validate:"required,len=6"`
 }
 
 // ResetPasswordRequest represents the reset password request body
 type ResetPasswordRequest struct {
-	ResetToken  string `json:"reset_token" binding:"required"`
-	NewPassword string `json:"new_password" binding:"required,min=8"`
+	ResetToken  string `json:"reset_token" validate:"required"`
+	NewPassword string `json:"new_password" validate:"required,min=8"`
 }
 
 // UpdateProfileRequest represents the profile update request body
 type UpdateProfileRequest struct {
-	Email     *string `json:"email" binding:"omitempty,email,max=254"`
-	FirstName *string `json:"first_name" binding:"omitempty,max=150"`
-	LastName  *string `json:"last_name" binding:"omitempty,max=150"`
+	Email     *string `json:"email" validate:"omitempty,email,max=254"`
+	FirstName *string `json:"first_name" validate:"omitempty,max=150"`
+	LastName  *string `json:"last_name" validate:"omitempty,max=150"`
 }
 
 // ResendVerificationRequest represents the resend verification email request
@@ -52,14 +52,14 @@ type ResendVerificationRequest struct {
 
 // AppleSignInRequest represents the Apple Sign In request body
 type AppleSignInRequest struct {
-	IDToken   string  `json:"id_token" binding:"required"`
-	UserID    string  `json:"user_id" binding:"required"` // Apple's sub claim
-	Email     *string `json:"email"`                      // May be nil or private relay
+	IDToken   string  `json:"id_token" validate:"required"`
+	UserID    string  `json:"user_id" validate:"required"` // Apple's sub claim
+	Email     *string `json:"email"`                       // May be nil or private relay
 	FirstName *string `json:"first_name"`
 	LastName  *string `json:"last_name"`
 }
 
 // GoogleSignInRequest represents the Google Sign In request body
 type GoogleSignInRequest struct {
-	IDToken string `json:"id_token" binding:"required"` // Google ID token from Credential Manager
+	IDToken string `json:"id_token" validate:"required"` // Google ID token from Credential Manager
 }