feat(scanner): add folder hash for smarter quick scan change detection (#4220)

* Simplify folder hash migration

* fix hashing lint

* refactor

Signed-off-by: Deluan <deluan@navidrome.org>

* Update scanner/folder_entry.go

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Signed-off-by: Deluan <deluan@navidrome.org>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

scanner/walk_dir_tree.go

@@ -9,78 +9,15 @@ import (
 	"slices"
 	"sort"
 	"strings"
-	"time"
 
 	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/consts"
-	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/utils"
-	"github.com/navidrome/navidrome/utils/chrono"
 	ignore "github.com/sabhiram/go-gitignore"
 )
 
-type folderEntry struct {
-	job             *scanJob
-	elapsed         chrono.Meter
-	path            string    // Full path
-	id              string    // DB ID
-	modTime         time.Time // From FS
-	updTime         time.Time // from DB
-	audioFiles      map[string]fs.DirEntry
-	imageFiles      map[string]fs.DirEntry
-	numPlaylists    int
-	numSubFolders   int
-	imagesUpdatedAt time.Time
-	tracks          model.MediaFiles
-	albums          model.Albums
-	albumIDMap      map[string]string
-	artists         model.Artists
-	tags            model.TagList
-	missingTracks   []*model.MediaFile
-}
-
-func (f *folderEntry) hasNoFiles() bool {
-	return len(f.audioFiles) == 0 && len(f.imageFiles) == 0 && f.numPlaylists == 0 && f.numSubFolders == 0
-}
-
-func (f *folderEntry) isNew() bool {
-	return f.updTime.IsZero()
-}
-
-func (f *folderEntry) toFolder() *model.Folder {
-	folder := model.NewFolder(f.job.lib, f.path)
-	folder.NumAudioFiles = len(f.audioFiles)
-	if core.InPlaylistsPath(*folder) {
-		folder.NumPlaylists = f.numPlaylists
-	}
-	folder.ImageFiles = slices.Collect(maps.Keys(f.imageFiles))
-	folder.ImagesUpdatedAt = f.imagesUpdatedAt
-	return folder
-}
-
-func newFolderEntry(job *scanJob, path string) *folderEntry {
-	id := model.FolderID(job.lib, path)
-	f := &folderEntry{
-		id:         id,
-		job:        job,
-		path:       path,
-		audioFiles: make(map[string]fs.DirEntry),
-		imageFiles: make(map[string]fs.DirEntry),
-		albumIDMap: make(map[string]string),
-		updTime:    job.popLastUpdate(id),
-	}
-	return f
-}
-
-func (f *folderEntry) isOutdated() bool {
-	if f.job.lib.FullScanInProgress {
-		return f.updTime.Before(f.job.lib.LastScanStartedAt)
-	}
-	return f.updTime.Before(f.modTime)
-}
-
 func walkDirTree(ctx context.Context, job *scanJob) (<-chan *folderEntry, error) {
 	results := make(chan *folderEntry)
 	go func() {