Fix backend API parity: document filters, task days param, i18n locales, contract tests

- Add document list filter support (residence, type, category, contractor, is_active, expiring_soon, search) to handler/service/repo
- Add `days` query param parsing to ListTasks handler (matches ListTasksByResidence)
- Add `error.invalid_token` i18n key to all 9 non-English locale files
- Update contract test to include VerificationResponse mapping

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/handlers/document_handler.go

@@ -14,6 +14,7 @@ import (
 	"github.com/treytartt/casera-api/internal/dto/requests"
 	"github.com/treytartt/casera-api/internal/middleware"
 	"github.com/treytartt/casera-api/internal/models"
+	"github.com/treytartt/casera-api/internal/repositories"
 	"github.com/treytartt/casera-api/internal/services"
 )
 
@@ -34,9 +35,45 @@ func NewDocumentHandler(documentService *services.DocumentService, storageServic
 // ListDocuments handles GET /api/documents/
 func (h *DocumentHandler) ListDocuments(c echo.Context) error {
 	user := c.Get(middleware.AuthUserKey).(*models.User)
-	response, err := h.documentService.ListDocuments(user.ID)
+
+	// Build filter from query params (matching KMP DocumentApi parameters)
+	var filter *repositories.DocumentFilter
+	if c.QueryParam("residence") != "" || c.QueryParam("document_type") != "" ||
+		c.QueryParam("category") != "" || c.QueryParam("contractor") != "" ||
+		c.QueryParam("is_active") != "" || c.QueryParam("expiring_soon") != "" ||
+		c.QueryParam("tags") != "" || c.QueryParam("search") != "" {
+		filter = &repositories.DocumentFilter{
+			DocumentType: c.QueryParam("document_type"),
+			Category:     c.QueryParam("category"),
+			Tags:         c.QueryParam("tags"),
+			Search:       c.QueryParam("search"),
+		}
+		if rid := c.QueryParam("residence"); rid != "" {
+			if parsed, err := strconv.ParseUint(rid, 10, 32); err == nil {
+				residenceID := uint(parsed)
+				filter.ResidenceID = &residenceID
+			}
+		}
+		if cid := c.QueryParam("contractor"); cid != "" {
+			if parsed, err := strconv.ParseUint(cid, 10, 32); err == nil {
+				contractorID := uint(parsed)
+				filter.ContractorID = &contractorID
+			}
+		}
+		if ia := c.QueryParam("is_active"); ia != "" {
+			isActive := ia == "true" || ia == "1"
+			filter.IsActive = &isActive
+		}
+		if es := c.QueryParam("expiring_soon"); es != "" {
+			if parsed, err := strconv.Atoi(es); err == nil {
+				filter.ExpiringSoon = &parsed
+			}
+		}
+	}
+
+	response, err := h.documentService.ListDocuments(user.ID, filter)
 	if err != nil {
-		return c.JSON(http.StatusInternalServerError, map[string]interface{}{"error": err.Error()})
+		return err
 	}
 	return c.JSON(http.StatusOK, response)
 }