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/scanner.go

@@ -8,7 +8,7 @@ import (
 
 	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/labstack/echo/v4"
+	"github.com/labstack/echo/v5"
 )
 
 const (
@@ -30,7 +30,7 @@ type ScanLibraryRequest struct {
 }
 
 // ScanLibrary handles POST /api/scanner/scan (now runs in background)
-func (h *Handler) ScanLibrary(c echo.Context) error {
+func (h *Handler) ScanLibrary(c *echo.Context) error {
 	var req ScanLibraryRequest
 
 	// Check if scan_request is set in context (from library scan route)
@@ -112,7 +112,7 @@ func (h *Handler) ScanLibrary(c echo.Context) error {
 }
 
 // StartScanner handles POST /api/scanner/start
-func (h *Handler) StartScanner(c echo.Context) error {
+func (h *Handler) StartScanner(c *echo.Context) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()
 
@@ -146,7 +146,7 @@ func (h *Handler) StartScanner(c echo.Context) error {
 }
 
 // StopScanner handles POST /api/scanner/stop
-func (h *Handler) StopScanner(c echo.Context) error {
+func (h *Handler) StopScanner(c *echo.Context) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()
 
@@ -157,7 +157,7 @@ func (h *Handler) StopScanner(c echo.Context) error {
 }
 
 // GetScanStatus handles GET /api/scanner/status/:jobId
-func (h *Handler) GetScanStatus(c echo.Context) error {
+func (h *Handler) GetScanStatus(c *echo.Context) error {
 	jobID := c.Param("jobId")
 
 	result, exists := h.worker.GetJobStatus(jobID)
@@ -238,7 +238,7 @@ func (h *Handler) StopWatchModeForLibrary(libraryID pgtype.UUID) error {
 }
 
 // StartWatchMode handles POST /api/scanner/watch/start
-func (h *Handler) StartWatchMode(c echo.Context) error {
+func (h *Handler) StartWatchMode(c *echo.Context) error {
 	userID := c.Get("user_id").(string)
 	userUUID, err := uuid.Parse(userID)
 	if err != nil {
@@ -272,7 +272,7 @@ func (h *Handler) StartWatchMode(c echo.Context) error {
 }
 
 // StopWatchMode handles POST /api/scanner/watch/stop
-func (h *Handler) StopWatchMode(c echo.Context) error {
+func (h *Handler) StopWatchMode(c *echo.Context) error {
 	var req struct {
 		LibraryID string `json:"library_id"`
 	}
@@ -300,7 +300,7 @@ func (h *Handler) StopWatchMode(c echo.Context) error {
 }
 
 // GetWatchModeStatus handles GET /api/scanner/watch/status
-func (h *Handler) GetWatchModeStatus(c echo.Context) error {
+func (h *Handler) GetWatchModeStatus(c *echo.Context) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()