scanner: fix library isolation, file mtime, force rescan, and deletion handling

Fix 1 - File modification time for created_at:
- Get file.ModTime() in processMediaFile and pass to CreateMediaItem
- Modified SQL INSERT to include created_at column

Fix 2 - Force rescan UPDATE instead of DELETE+INSERT:
- Changed force rescan logic to call updateMediaItem instead of delete + create
- Preserves created_at timestamp on force rescan

Fix 3 - GetMediaItemByFilePath filters by library_id:
- Added library_id to WHERE clause in SQL query
- Created GetMediaItemByFilePathAnyLibrary for cross-library lookups (KOReader)
- Added SetLibraryID method to MediaScanner
- Updated handler to call SetLibraryID for watch mode

Fix 4 - File deletion handling with persistent logging:
- Added fsnotify.Remove handler in WatchChanges
- Added orphan cleanup in ScanFolders after scan completes
- Created scanner_logger.go with daily log rotation (7 days)
- Logs to /app/logs/scanner-deletes-YYYY-MM-DD.log and scanner-errors-YYYY-MM-DD.log
- Individual deletes with enhanced safety logging

Note: Integration tests can now safely scan /app/uploads because
GetMediaItemByFilePath now filters by library_id, preventing
cross-library interference.

internal/services/scanner_logger.go

@@ -0,0 +1,107 @@
+package services
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+const (
+	logDir        = "/app/logs"
+	maxLogAgeDays = 7
+)
+
+type ScannerLogger struct {
+	deletesFile *os.File
+	errorsFile  *os.File
+	currentDate string
+}
+
+func NewScannerLogger() *ScannerLogger {
+	return &ScannerLogger{}
+}
+
+func (l *ScannerLogger) ensureLogFiles() error {
+	today := time.Now().Format("2006-01-02")
+
+	if l.currentDate == today && l.deletesFile != nil {
+		return nil
+	}
+
+	if l.deletesFile != nil {
+		l.deletesFile.Close()
+	}
+	if l.errorsFile != nil {
+		l.errorsFile.Close()
+	}
+
+	if err := os.MkdirAll(logDir, 0755); err != nil {
+		return fmt.Errorf("failed to create log directory: %v", err)
+	}
+
+	deletesPath := filepath.Join(logDir, fmt.Sprintf("scanner-deletes-%s.log", today))
+	errorsPath := filepath.Join(logDir, fmt.Sprintf("scanner-errors-%s.log", today))
+
+	deletesFile, err := os.OpenFile(deletesPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return fmt.Errorf("failed to open deletes log file: %v", err)
+	}
+
+	errorsFile, err := os.OpenFile(errorsPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		deletesFile.Close()
+		return fmt.Errorf("failed to open errors log file: %v", err)
+	}
+
+	l.deletesFile = deletesFile
+	l.errorsFile = errorsFile
+	l.currentDate = today
+
+	l.cleanupOldLogs()
+
+	return nil
+}
+
+func (l *ScannerLogger) cleanupOldLogs() {
+	cutoff := time.Now().AddDate(0, 0, -maxLogAgeDays)
+
+	filepath.Walk(logDir, func(path string, info os.FileInfo, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+		if !info.IsDir() && info.ModTime().Before(cutoff) {
+			os.Remove(path)
+		}
+		return nil
+	})
+}
+
+func (l *ScannerLogger) LogDelete(message string) {
+	if err := l.ensureLogFiles(); err != nil {
+		fmt.Printf("ERROR: Failed to ensure log files: %v\n", err)
+		return
+	}
+	timestamp := time.Now().Format("2006-01-02 15:04:05")
+	logLine := fmt.Sprintf("[%s] %s\n", timestamp, message)
+	l.deletesFile.WriteString(logLine)
+}
+
+func (l *ScannerLogger) LogError(message string) {
+	if err := l.ensureLogFiles(); err != nil {
+		fmt.Printf("ERROR: Failed to ensure log files: %v\n", err)
+		return
+	}
+	timestamp := time.Now().Format("2006-01-02 15:04:05")
+	logLine := fmt.Sprintf("[%s] %s\n", timestamp, message)
+	l.errorsFile.WriteString(logLine)
+}
+
+func (l *ScannerLogger) Close() {
+	if l.deletesFile != nil {
+		l.deletesFile.Close()
+	}
+	if l.errorsFile != nil {
+		l.errorsFile.Close()
+	}
+}