feat(playlist): improve movie curation workflow

[dogbertdev]

Summary

• Add movies --keys-only, movie de-dupe modes, and OR-style repeated filters for easier curation.
• Add playlist creation from files/stdin plus dry-run preview support.
• Add playlist sort for regular playlists, using Plex playlist item IDs and supporting dry-run previews.
• Add exact-ID metadata tag edits via library item edit --add-tag/--remove-tag for safer curated collections.
• Preserve original titles/actor roles in movie metadata and fix paged library item fetching/cache keys for large combined libraries.
• Document the workflow improvements and add regression coverage.

Review Feedback

• Addressed review feedback by filtering GetMovies results to type=movie before returning/filtering results, with regression coverage for show/episode leakage.
• Followed up with a structural refactor that moves movie filtering/dedupe into internal/plexclient/movies.go and makes playlist sort issue only the Plex move operations that are actually needed.

Live Plex Work

• Updated the Martial Arts playlist to 54 items after adding the newly available films.
• Repaired the Martial Arts collection in Movies (Combined): removed the accidental all-movies tag and re-added it only to the 53 playlist items present in Combined.
• Sorted the Martial Arts playlist by year ascending; verified the saved order starts at 1954 and ends at 2025.
• Left 50639 / Mr. Vampire in unsorted movies; it is not present in the section-14 Combined listing.

Validation

• go test ./...
• make lint test (golangci-lint skipped locally because it is not installed; all tests passed)
• Pre-push hook: import formatting, golangci-lint, tests
• Live CLI smoke checks for playlist add/show, playlist sort dry-run/apply, collection discovery, exact-ID tag edit, and collection membership comparison

[chatgpt-codex-connector]

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