Refactor handlers package to separate common handler logic

Extract Handler struct, constructor, and shared utilities from scanner.go
into a new commonhandlers.go file for better code organization.

Changes:
- Move Handler struct definition to commonhandlers.go
- Move NewHandler constructor to commonhandlers.go
- Move SetupRoutes function to commonhandlers.go
- Move parseDate utility function to commonhandlers.go
- Remove unused imports from scanner.go
- Create dedicated commonhandlers.go for shared HTTP handler code

This refactoring improves code maintainability by separating
concerns between scanner-specific logic and common handler utilities,
making it easier to understand and extend the handlers package.

internal/handlers/commonhandlers.go

@@ -0,0 +1,71 @@
+package handlers
+
+import (
+	"bookhoard/internal/database"
+	"bookhoard/internal/services"
+	wsync "bookhoard/internal/sync"
+	"context"
+	"sync"
+	"time"
+
+	"github.com/labstack/echo/v4"
+)
+
+type Handler struct {
+	db                *database.Queries
+	scanner           *services.MediaScanner
+	worker            *services.Worker
+	scheduler         *services.Scheduler
+	queueProcessor    *wsync.SyncQueueProcessor
+	queueCtx          context.Context
+	queueCancel       context.CancelFunc
+	ctx               context.Context
+	cancel            context.CancelFunc
+	mu                sync.Mutex
+	watchModeCtx      context.Context
+	watchModeCancel   context.CancelFunc
+	watchingLibraries map[string]bool
+	connManager       *wsync.ConnectionManager
+	cleanupTaskCancel context.CancelFunc
+}
+
+func NewHandler(db *database.Queries, connManager *wsync.ConnectionManager, queueProcessor *wsync.SyncQueueProcessor) *Handler {
+	ctx, cancel := context.WithCancel(context.Background())
+	worker := services.NewWorker(3)
+	scheduler := services.NewScheduler(worker, db)
+
+	queueCtx, queueCancel := context.WithCancel(context.Background())
+
+	watchCtx, watchCancel := context.WithCancel(context.Background())
+
+	return &Handler{
+		db:                db,
+		scanner:           services.NewMediaScanner(db),
+		worker:            worker,
+		scheduler:         scheduler,
+		queueProcessor:    queueProcessor,
+		queueCtx:          queueCtx,
+		queueCancel:       queueCancel,
+		ctx:               ctx,
+		cancel:            cancel,
+		watchModeCtx:      watchCtx,
+		watchModeCancel:   watchCancel,
+		watchingLibraries: make(map[string]bool),
+		connManager:       connManager,
+	}
+}
+
+// parseDate parses a date string in YYYY-MM-DD format
+func parseDate(dateStr string) time.Time {
+	if dateStr == "" {
+		return time.Time{}
+	}
+	if t, err := time.Parse("2006-01-02", dateStr); err == nil {
+		return t
+	}
+	return time.Time{}
+}
+
+func SetupRoutes(g *echo.Group, db *database.Queries, connManager *wsync.ConnectionManager, queueProcessor *wsync.SyncQueueProcessor) *Handler {
+	return NewHandler(db, connManager, queueProcessor)
+}

internal/handlers/scanner.go

@@ -1,14 +1,10 @@
 package handlers
 
 import (
-	"bookhoard/internal/database"
 	"bookhoard/internal/services"
-	wsync "bookhoard/internal/sync"
 	"context"
 	"fmt"
 	"net/http"
-	"sync"
-	"time"
 
 	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5/pgtype"
@@ -19,50 +15,6 @@ const (
 	maxPaginationLimit = 1000
 )
 
-type Handler struct {
-	db                *database.Queries
-	scanner           *services.MediaScanner
-	worker            *services.Worker
-	scheduler         *services.Scheduler
-	queueProcessor    *wsync.SyncQueueProcessor
-	queueCtx          context.Context
-	queueCancel       context.CancelFunc
-	ctx               context.Context
-	cancel            context.CancelFunc
-	mu                sync.Mutex
-	watchModeCtx      context.Context
-	watchModeCancel   context.CancelFunc
-	watchingLibraries map[string]bool
-	connManager       *wsync.ConnectionManager
-	cleanupTaskCancel context.CancelFunc
-}
-
-func NewHandler(db *database.Queries, connManager *wsync.ConnectionManager, queueProcessor *wsync.SyncQueueProcessor) *Handler {
-	ctx, cancel := context.WithCancel(context.Background())
-	worker := services.NewWorker(3)
-	scheduler := services.NewScheduler(worker, db)
-
-	queueCtx, queueCancel := context.WithCancel(context.Background())
-
-	watchCtx, watchCancel := context.WithCancel(context.Background())
-
-	return &Handler{
-		db:                db,
-		scanner:           services.NewMediaScanner(db),
-		worker:            worker,
-		scheduler:         scheduler,
-		queueProcessor:    queueProcessor,
-		queueCtx:          queueCtx,
-		queueCancel:       queueCancel,
-		ctx:               ctx,
-		cancel:            cancel,
-		watchModeCtx:      watchCtx,
-		watchModeCancel:   watchCancel,
-		watchingLibraries: make(map[string]bool),
-		connManager:       connManager,
-	}
-}
-
 // StartBackgroundTasks starts the queue processor and cleanup task
 // This should be called once for the main handler instance
 func (h *Handler) StartBackgroundTasks() {
@@ -70,21 +22,6 @@ func (h *Handler) StartBackgroundTasks() {
 	go h.queueProcessor.Start(h.queueCtx)
 }
 
-// parseDate parses a date string in YYYY-MM-DD format
-func parseDate(dateStr string) time.Time {
-	if dateStr == "" {
-		return time.Time{}
-	}
-	if t, err := time.Parse("2006-01-02", dateStr); err == nil {
-		return t
-	}
-	return time.Time{}
-}
-
-func SetupRoutes(g *echo.Group, db *database.Queries, connManager *wsync.ConnectionManager, queueProcessor *wsync.SyncQueueProcessor) *Handler {
-	return NewHandler(db, connManager, queueProcessor)
-}
-
 // ScanLibraryRequest represents the request for scanning a library
 type ScanLibraryRequest struct {
 	FolderPaths []string `json:"folder_paths,omitempty"`