refactor(handlers): update all handlers for Echo v5 compatibility

Update all handler functions to use *echo.Context (pointer) instead of echo.Context (value) as required by Echo v5.

Changes across all handler files:
- analytics.go: Update handler signatures
- auth.go: Update authentication handler signatures
- book_matching.go: Update matching handler signatures
- collections.go: Update collection handler signatures
- collections_preview_test.go: Update test signatures
- commonhandlers.go: Update common handler signatures
- conflicts.go: Update conflict handler signatures
- context.go: Update context handler signatures
- dashboard.go: Update dashboard handler signatures
- devices.go: Update device handler signatures
- jobs.go: Update job handler signatures
- kobo.go: Update Kobo handler signatures
- koreader.go: Update Koreader handler signatures
- library.go: Update library handler signatures
- matching.go: Update matching handler signatures
- media.go: Update media handler signatures
- opds.go: Update OPDS handler signatures
- progress.go: Update progress handler signatures
- queue.go: Update queue handler signatures
- refresh_token.go: Update token handler signatures
- scanner.go: Update scanner handler signatures
- sidecar.go: Update sidecar handler signatures
- sync.go: Update sync handler signatures
- system_settings.go: Update settings handler signatures
- websocket.go: Update WebSocket handler signatures

All handlers now properly implement Echo v5's pointer-based context pattern.
This change is necessary for type safety and compatibility with Echo v5's
improved context handling and WebSocket support.

internal/handlers/auth.go

@@ -16,7 +16,7 @@ import (
 	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/labstack/echo/v4"
+	"github.com/labstack/echo/v5"
 	"golang.org/x/crypto/bcrypt"
 )
 
@@ -95,7 +95,7 @@ type AdminUpdateUserRequest struct {
 }
 
 // Register handles POST /api/auth/register
-func (h *AuthHandler) Register(c echo.Context) error {
+func (h *AuthHandler) Register(c *echo.Context) error {
 	email := c.FormValue("email")
 	username := c.FormValue("username")
 	password := c.FormValue("password")
@@ -300,7 +300,7 @@ window.location.href = '/dashboard';
 }
 
 // Login handles POST /api/auth/login
-func (h *AuthHandler) Login(c echo.Context) error {
+func (h *AuthHandler) Login(c *echo.Context) error {
 	login := c.FormValue("login")
 	password := c.FormValue("password")
 
@@ -452,7 +452,7 @@ window.location.href = '%s';
 }
 
 // GetProfile handles GET /api/auth/profile
-func (h *AuthHandler) GetProfile(c echo.Context) error {
+func (h *AuthHandler) GetProfile(c *echo.Context) error {
 	user := MustGetAuthenticatedUser(c)
 
 	firstName := ""
@@ -475,7 +475,7 @@ func (h *AuthHandler) GetProfile(c echo.Context) error {
 
 // UpdateProfile handles PUT /api/auth/profile (self-edit) and PUT /api/auth/profile/:id (admin edit)
 // Combined handler for both self-service and admin profile updates
-func (h *AuthHandler) UpdateProfile(c echo.Context) error {
+func (h *AuthHandler) UpdateProfile(c *echo.Context) error {
 	currentUser := MustGetAuthenticatedUser(c)
 
 	// Determine target user: URL param (admin mode) or current user (self-edit)
@@ -603,7 +603,7 @@ func (h *AuthHandler) UpdateProfile(c echo.Context) error {
 }
 
 // ListUsers handles GET /api/auth/users
-func (h *AuthHandler) ListUsers(c echo.Context) error {
+func (h *AuthHandler) ListUsers(c *echo.Context) error {
 	users, err := h.db.ListUsers(c.Request().Context())
 	if err != nil {
 		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
@@ -641,7 +641,7 @@ type UpdateThemeRequest struct {
 }
 
 // UpdateTheme handles PUT /api/auth/theme
-func (h *AuthHandler) UpdateTheme(c echo.Context) error {
+func (h *AuthHandler) UpdateTheme(c *echo.Context) error {
 	user := MustGetAuthenticatedUser(c)
 
 	var req UpdateThemeRequest
@@ -668,7 +668,7 @@ type UpdateUsernameRequest struct {
 }
 
 // UpdateUsername handles PUT /api/auth/username
-func (h *AuthHandler) UpdateUsername(c echo.Context) error {
+func (h *AuthHandler) UpdateUsername(c *echo.Context) error {
 	user := MustGetAuthenticatedUser(c)
 
 	var req UpdateUsernameRequest
@@ -702,7 +702,7 @@ type UpdateEmailRequest struct {
 }
 
 // UpdateEmail handles PUT /api/auth/email
-func (h *AuthHandler) UpdateEmail(c echo.Context) error {
+func (h *AuthHandler) UpdateEmail(c *echo.Context) error {
 	user := MustGetAuthenticatedUser(c)
 
 	var req UpdateEmailRequest
@@ -739,7 +739,7 @@ type UpdatePasswordRequest struct {
 
 // UpdatePassword handles PUT /api/auth/password (self-change) and PUT /api/auth/password/:id (admin reset)
 // Combined handler for both self-service password change and admin password reset
-func (h *AuthHandler) UpdatePassword(c echo.Context) error {
+func (h *AuthHandler) UpdatePassword(c *echo.Context) error {
 	currentUser := MustGetAuthenticatedUser(c)
 
 	// Determine target user: URL param (admin mode) or current user (self-change)
@@ -820,7 +820,7 @@ func (h *AuthHandler) UpdatePassword(c echo.Context) error {
 
 // DeleteUser handles DELETE /api/auth/profile (self-deletion) and DELETE /api/auth/profile/:id (admin deletion)
 // Combined handler for both self-deletion and admin deletion of users
-func (h *AuthHandler) DeleteUser(c echo.Context) error {
+func (h *AuthHandler) DeleteUser(c *echo.Context) error {
 	currentUser := MustGetAuthenticatedUser(c)
 
 	// Get target user ID from URL param (admin mode) or use current user (self-deletion)
@@ -912,7 +912,7 @@ type UpdateUserMaxDevicesRequest struct {
 }
 
 // UpdateUserMaxDevices handles PUT /api/auth/users/:id/max-devices (admin only)
-func (h *AuthHandler) UpdateUserMaxDevices(c echo.Context) error {
+func (h *AuthHandler) UpdateUserMaxDevices(c *echo.Context) error {
 	userID := c.Param("id")
 	if userID == "" {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "user id required"})
@@ -949,7 +949,7 @@ func (h *AuthHandler) UpdateUserMaxDevices(c echo.Context) error {
 
 // AdminMiddleware checks if the user has admin role
 func AdminMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
-	return func(c echo.Context) error {
+	return func(c *echo.Context) error {
 		userRole, exists := c.Get("user_role").(string)
 		if !exists || userRole != "admin" {
 			return c.JSON(http.StatusForbidden, map[string]string{"error": "admin access required"})