Add comprehensive kanban board tests and fix test suite

- Add 13 tests for task kanban categorization and button types
- Fix i18n initialization in test setup (was causing nil pointer panics)
- Add TaskCompletionImage to test DB auto-migrate
- Update ListTasks tests to expect kanban board response instead of array

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

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

internal/testutil/testutil.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"sync"
 	"testing"
 
 	"github.com/gin-gonic/gin"
@@ -13,11 +14,19 @@ import (
 	"gorm.io/gorm"
 	"gorm.io/gorm/logger"
 
+	"github.com/treytartt/casera-api/internal/i18n"
 	"github.com/treytartt/casera-api/internal/models"
 )
 
+var i18nOnce sync.Once
+
 // SetupTestDB creates an in-memory SQLite database for testing
 func SetupTestDB(t *testing.T) *gorm.DB {
+	// Initialize i18n once for all tests
+	i18nOnce.Do(func() {
+		i18n.Init()
+	})
+
 	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
 		Logger: logger.Default.LogMode(logger.Silent),
 	})
@@ -40,6 +49,7 @@ func SetupTestDB(t *testing.T) *gorm.DB {
 		&models.TaskStatus{},
 		&models.TaskFrequency{},
 		&models.TaskCompletion{},
+		&models.TaskCompletionImage{},
 		&models.Contractor{},
 		&models.ContractorSpecialty{},
 		&models.Document{},