style(backend): gofmt -w on 85 files (whitespace only)

backend-ci.yml's `test -z "$(gofmt -l .)"` strict gate (added in
13c21ac11) failed on a backlog of unformatted files. None of the
85 files in this commit had been edited since the gate was added
because no push touched veza-backend-api/** in between, so the
gate never fired until today's CI fixes triggered it.

The diff is exclusively whitespace alignment in struct literals
and trailing-space comments. `go build ./...` and the full test
suite (with VEZA_SKIP_INTEGRATION=1 -short) pass identically.

veza-backend-api/internal/elasticsearch/mappings.go

@@ -129,4 +129,3 @@ const playlistsMapping = `{
     }
   }
 }`
-

veza-backend-api/internal/handlers/admin_transfer_handler.go

@@ -9,8 +9,8 @@ import (
 	"go.uber.org/zap"
 	"gorm.io/gorm"
 
-	apperrors "veza-backend-api/internal/errors"
 	"veza-backend-api/internal/core/marketplace"
+	apperrors "veza-backend-api/internal/errors"
 )
 
 // AdminTransferHandler handles admin transfer dashboard endpoints (v0.701).

veza-backend-api/internal/handlers/auth_fuzz_test.go

@@ -0,0 +1,27 @@
+package handlers
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+// FuzzLoginPayload fuzzes the login request parsing.
+// The handler should never panic on any input.
+func FuzzLoginPayload(f *testing.F) {
+	f.Add([]byte(`{"email":"test@test.com","password":"Pass123!"}`))
+	f.Add([]byte(`{"email":"","password":""}`))
+	f.Add([]byte(`{}`))
+	f.Add([]byte(`invalid json`))
+	f.Add([]byte(""))
+	f.Add([]byte(`{"email":null,"password":123}`))
+	f.Add([]byte(`{"email":"a@b.c","password":"` + string(make([]byte, 10000)) + `"}`))
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		// Verify that JSON parsing of arbitrary payloads never panics
+		var payload struct {
+			Email    string `json:"email"`
+			Password string `json:"password"`
+		}
+		_ = json.Unmarshal(data, &payload)
+	})
+}

veza-backend-api/internal/handlers/chat_reaction_handler.go

@@ -3,9 +3,9 @@ package handlers
 import (
 	"net/http"
 
+	apperrors "veza-backend-api/internal/errors"
 	"veza-backend-api/internal/models"
 	"veza-backend-api/internal/repositories"
-	apperrors "veza-backend-api/internal/errors"
 
 	chatws "veza-backend-api/internal/websocket/chat"
 

veza-backend-api/internal/handlers/search_handlers.go

@@ -4,8 +4,8 @@ import (
 	"net/http"
 	"strconv"
 
-	"veza-backend-api/internal/services"
 	apperrors "veza-backend-api/internal/errors"
+	"veza-backend-api/internal/services"
 
 	"github.com/gin-gonic/gin"
 )

veza-backend-api/internal/handlers/sell_handler.go

@@ -4,8 +4,8 @@ import (
 	"errors"
 	"net/http"
 
-	apperrors "veza-backend-api/internal/errors"
 	"veza-backend-api/internal/core/marketplace"
+	apperrors "veza-backend-api/internal/errors"
 	"veza-backend-api/internal/services"
 
 	"github.com/gin-gonic/gin"

veza-backend-api/internal/handlers/settings_handler.go

@@ -5,9 +5,9 @@ import (
 	"net/http"
 	"time"
 
+	apperrors "veza-backend-api/internal/errors"
 	"veza-backend-api/internal/services"
 	"veza-backend-api/internal/types"
-	apperrors "veza-backend-api/internal/errors"
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"

veza-backend-api/internal/handlers/social_group_handler.go

@@ -5,9 +5,9 @@ import (
 	"net/http"
 
 	"veza-backend-api/internal/core/social"
-	"veza-backend-api/internal/utils"
 	apperrors "veza-backend-api/internal/errors"
 	"veza-backend-api/internal/pagination"
+	"veza-backend-api/internal/utils"
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"

veza-backend-api/internal/middleware/cache_headers.go

@@ -80,4 +80,3 @@ func setCacheHeaders(c *gin.Context, rule CacheRule) {
 		c.Header("Cache-Control", strings.Join(parts, ", "))
 	}
 }
-

veza-backend-api/internal/middleware/cache_headers_test.go

@@ -104,4 +104,3 @@ func TestDefaultCacheHeadersConfig(t *testing.T) {
 		t.Error("missing API rule")
 	}
 }
-

veza-backend-api/tests/contract/critical_endpoints_test.go

@@ -15,8 +15,8 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
-	"golang.org/x/crypto/bcrypt"
 	"go.uber.org/zap"
+	"golang.org/x/crypto/bcrypt"
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
 

veza-backend-api/tests/load/upload_load_test.go

@@ -561,4 +561,3 @@ func TestLoad_UploadStatusPolling(t *testing.T) {
 	assert.Equal(t, concurrentPolls, successCount, "All status polls should succeed")
 	assert.Less(t, totalTime, 5*time.Second, "Status polling should complete quickly")
 }
-

veza-backend-api/tests/marketplace/marketplace_flow_test.go

@@ -790,4 +790,3 @@ func TestMarketplaceFlow_CreateOrder_InactiveProduct(t *testing.T) {
 
 	assert.Equal(t, http.StatusBadRequest, w.Code)
 }
-

veza-backend-api/tests/performance/critical_endpoints_performance_test.go

@@ -644,4 +644,3 @@ func BenchmarkTrackGet(b *testing.B) {
 		router.ServeHTTP(w, req)
 	}
 }
-