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/handlers/media_handler.go

@@ -1,13 +1,13 @@
 package handlers
 
 import (
-	"net/http"
 	"path/filepath"
 	"strconv"
 	"strings"
 
-	"github.com/gin-gonic/gin"
+	"github.com/labstack/echo/v4"
 
+	"github.com/treytartt/casera-api/internal/apperrors"
 	"github.com/treytartt/casera-api/internal/middleware"
 	"github.com/treytartt/casera-api/internal/models"
 	"github.com/treytartt/casera-api/internal/repositories"
@@ -39,132 +39,117 @@ func NewMediaHandler(
 
 // ServeDocument serves a document file with access control
 // GET /api/media/document/:id
-func (h *MediaHandler) ServeDocument(c *gin.Context) {
-	user := c.MustGet(middleware.AuthUserKey).(*models.User)
+func (h *MediaHandler) ServeDocument(c echo.Context) error {
+	user := c.Get(middleware.AuthUserKey).(*models.User)
 
 	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
 	if err != nil {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid document ID"})
-		return
+		return apperrors.BadRequest("error.invalid_id")
 	}
 
 	// Get document
 	doc, err := h.documentRepo.FindByID(uint(id))
 	if err != nil {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Document not found"})
-		return
+		return apperrors.NotFound("error.document_not_found")
 	}
 
 	// Check access to residence
 	hasAccess, err := h.residenceRepo.HasAccess(doc.ResidenceID, user.ID)
 	if err != nil || !hasAccess {
-		c.JSON(http.StatusForbidden, gin.H{"error": "Access denied"})
-		return
+		return apperrors.Forbidden("error.access_denied")
 	}
 
 	// Serve the file
 	filePath := h.resolveFilePath(doc.FileURL)
 	if filePath == "" {
-		c.JSON(http.StatusNotFound, gin.H{"error": "File not found"})
-		return
+		return apperrors.NotFound("error.file_not_found")
 	}
 
 	// Set caching headers (private, 1 hour)
-	c.Header("Cache-Control", "private, max-age=3600")
-	c.File(filePath)
+	c.Response().Header().Set("Cache-Control", "private, max-age=3600")
+	return c.File(filePath)
 }
 
 // ServeDocumentImage serves a document image with access control
 // GET /api/media/document-image/:id
-func (h *MediaHandler) ServeDocumentImage(c *gin.Context) {
-	user := c.MustGet(middleware.AuthUserKey).(*models.User)
+func (h *MediaHandler) ServeDocumentImage(c echo.Context) error {
+	user := c.Get(middleware.AuthUserKey).(*models.User)
 
 	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
 	if err != nil {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid image ID"})
-		return
+		return apperrors.BadRequest("error.invalid_id")
 	}
 
 	// Get document image
 	img, err := h.documentRepo.FindImageByID(uint(id))
 	if err != nil {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Image not found"})
-		return
+		return apperrors.NotFound("error.image_not_found")
 	}
 
 	// Get parent document to check residence access
 	doc, err := h.documentRepo.FindByID(img.DocumentID)
 	if err != nil {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Parent document not found"})
-		return
+		return apperrors.NotFound("error.document_not_found")
 	}
 
 	// Check access to residence
 	hasAccess, err := h.residenceRepo.HasAccess(doc.ResidenceID, user.ID)
 	if err != nil || !hasAccess {
-		c.JSON(http.StatusForbidden, gin.H{"error": "Access denied"})
-		return
+		return apperrors.Forbidden("error.access_denied")
 	}
 
 	// Serve the file
 	filePath := h.resolveFilePath(img.ImageURL)
 	if filePath == "" {
-		c.JSON(http.StatusNotFound, gin.H{"error": "File not found"})
-		return
+		return apperrors.NotFound("error.file_not_found")
 	}
 
-	c.Header("Cache-Control", "private, max-age=3600")
-	c.File(filePath)
+	c.Response().Header().Set("Cache-Control", "private, max-age=3600")
+	return c.File(filePath)
 }
 
 // ServeCompletionImage serves a task completion image with access control
 // GET /api/media/completion-image/:id
-func (h *MediaHandler) ServeCompletionImage(c *gin.Context) {
-	user := c.MustGet(middleware.AuthUserKey).(*models.User)
+func (h *MediaHandler) ServeCompletionImage(c echo.Context) error {
+	user := c.Get(middleware.AuthUserKey).(*models.User)
 
 	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
 	if err != nil {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid image ID"})
-		return
+		return apperrors.BadRequest("error.invalid_id")
 	}
 
 	// Get completion image
 	img, err := h.taskRepo.FindCompletionImageByID(uint(id))
 	if err != nil {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Image not found"})
-		return
+		return apperrors.NotFound("error.image_not_found")
 	}
 
 	// Get the completion to get the task
 	completion, err := h.taskRepo.FindCompletionByID(img.CompletionID)
 	if err != nil {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Completion not found"})
-		return
+		return apperrors.NotFound("error.completion_not_found")
 	}
 
 	// Get task to check residence access
 	task, err := h.taskRepo.FindByID(completion.TaskID)
 	if err != nil {
-		c.JSON(http.StatusNotFound, gin.H{"error": "Task not found"})
-		return
+		return apperrors.NotFound("error.task_not_found")
 	}
 
 	// Check access to residence
 	hasAccess, err := h.residenceRepo.HasAccess(task.ResidenceID, user.ID)
 	if err != nil || !hasAccess {
-		c.JSON(http.StatusForbidden, gin.H{"error": "Access denied"})
-		return
+		return apperrors.Forbidden("error.access_denied")
 	}
 
 	// Serve the file
 	filePath := h.resolveFilePath(img.ImageURL)
 	if filePath == "" {
-		c.JSON(http.StatusNotFound, gin.H{"error": "File not found"})
-		return
+		return apperrors.NotFound("error.file_not_found")
 	}
 
-	c.Header("Cache-Control", "private, max-age=3600")
-	c.File(filePath)
+	c.Response().Header().Set("Cache-Control", "private, max-age=3600")
+	return c.File(filePath)
 }
 
 // resolveFilePath converts a stored URL to an actual file path