feat: add movie release date cutoff filter

[Primexz]

Summary

Adds a per-library movie_release_date_max filter for Radarr movie cleanup candidates.

When configured, movies are only eligible for deletion if their release date is before the configured cutoff date. Movies released on or after the cutoff are skipped. Non-movie media continues through the filter unchanged, and leaving the setting empty disables the release-date filter.

Use case

This lets users delete older, unwatched movies while protecting newer releases from cleanup. For example, a library can allow movies released before 2024 to be considered for deletion when they also satisfy the existing age, stream, size, and tag filters, while keeping movies released in 2024 or later.

Details

• Adds movie_release_date_max to filter config.
• Supports YYYY-MM-DD and RFC3339-style timestamps.
• Registers the movie release filter in the cleanup pipeline.
• Uses the earliest known Radarr movie release date from release date, cinema, digital, or physical release fields.
• Documents the new setting in the README.
• Adds tests for cutoff behavior, disabled config behavior, and earliest-release-date selection.

Validation

• go test ./internal/filter/movie_release_filter

[jon4hz]

Hey @Primexz, thanks a lot for the contribution!