- Add TestResolveM3UPath with 7 cases: abs, relative, second root, no match, empty roots, nil knownPaths
- Add TestToRelativePathMultiRoot with 5 cases: first root, second root, no root, empty roots, empty string
- Add TestRemoveM3UEntriesMultiRoot: entries from different roots removed correctly
- Add TestFindM3UEntryMultiRoot: entry relative to second root found
- Add TestReplaceM3UEntryPathsMultiRoot: replacement under second root applied
- Replace getLibraryRoot() with getAllLibraryRoots() returning all library paths
- Add resolveM3UPath() for multi-root resolution with knownPaths lookup
- Add toRelativePathMultiRoot() to save relative paths using correct root
- Update removeM3UEntries, replaceM3UEntryPaths, findM3UEntry for []string roots
- Update all 8 call sites in playlist.go for multi-root resolution
- Update existing test signatures for new []string parameter types
- Fix pre-existing golines formatting in scan_queue.go
yonlu