Migrate mm-core metadata I/O to MeedyaSuite-core

[Salem874]

Summary

Replace mm-core/src/metadata/ (1886 lines) with MeedyaSuite-core's meedya-metadata tag I/O module and tag registry. The core library provides format-agnostic metadata reading/writing via lofty, supporting MP4, ID3v2, Vorbis, APE, and RIFF formats.

What changes

Replace tag I/O operations

Replace mm-core's metadata read/write code with meedya_metadata::tag_io:

mm-core function	MeedyaSuite-core replacement
Tag reading	meedya_metadata::tag_io::extract_tags(path) -> HashMap<String, String>
Tag writing	meedya_metadata::tag_io::write_tags(path, &HashMap<String, String>)
Cover art extraction	meedya_metadata::tag_io::extract_cover_art(path) -> Option<Vec<u8>>
Cover art embedding	meedya_metadata::tag_io::embed_cover_art(path, data, mime_type)
Audio properties	meedya_metadata::tag_io::extract_audio_properties(path) -> AudioProperties
Tag removal	meedya_metadata::tag_io::remove_tag(path, key)

Replace tag registry

Replace mm-core's tag constants and definitions with meedya_metadata::tag_registry:

TagRegistry (crates/meedya-metadata/src/tag_registry.rs):

• TagRegistry::from_toml(toml_str) — parse custom tag definitions
• DEFAULT_REGISTRY static — built-in tag definitions loaded from config/tags.toml
• TagScope::Album / TagScope::Track — scope-based tag lookup
• registry.get(scope, id) -> Option<&TagDefinition> — tag lookup
• registry.all_paths() — list all JSON paths for audit diffing
• extract_json_value(json, path) — dotted-path JSON extraction with array indexing
• value_to_string(value, value_type) — type-aware JSON-to-string conversion

Standardized tag constants (meedya_metadata::tag_registry::tags):

• Standard: TITLE, ARTIST, ALBUM, ALBUM_ARTIST, GENRE, YEAR, TRACK_NUMBER, DISC_NUMBER, COMPOSER, COMMENT, COPYRIGHT, LYRICS
• Identifiers: ISRC, UPC, RECORD_LABEL, RELEASE_DATE, CONTENT_RATING
• Sort keys: TITLE_SORT, ARTIST_SORT, ALBUM_SORT, ALBUM_ARTIST_SORT, COMPOSER_SORT
• Classical: WORK, MOVEMENT, MOVEMENT_NUMBER, MOVEMENT_COUNT
• ReplayGain: REPLAYGAIN_TRACK_GAIN, REPLAYGAIN_TRACK_PEAK, REPLAYGAIN_ALBUM_GAIN, REPLAYGAIN_ALBUM_PEAK
• MeedyaSuite: SOURCE_STORE, ENCODE_SOURCE, SPATIAL_TYPE, CHANNEL_CONFIG, IS_LOSSLESS, IS_BINAURAL, IS_DOWNMIX

AudioProperties struct: duration_ms, sample_rate, bit_depth, channels, bitrate

Key mapping (tag_io::string_to_item_key): Automatic mapping of standard keys (isrc, composer, conductor, encoder, copyright, lyrics, album_artist, release_date, record_label, sort keys, work, movement) to format-specific ItemKey values.

Error types

Use meedya_metadata::error::TagError:

• ReadFailed(String) — file read errors
• WriteFailed(String) — tag write errors
• UnsupportedFormat(String) — unsupported audio format
• TagNotFound(String) — tag lookup failures

Migration steps

1. Replace direct tag reading code with meedya_metadata::tag_io::extract_tags(path)
2. Replace tag writing code with meedya_metadata::tag_io::write_tags(path, &tags)
3. Replace cover art operations with extract_cover_art / embed_cover_art
4. Replace hardcoded tag name strings with meedya_metadata::tag_registry::tags::* constants
5. Replace custom TOML tag registry loading with meedya_metadata::tag_registry::DEFAULT_REGISTRY
6. Replace mp4ameta direct usage with lofty-based tag_io (supports more formats)
7. Delete mm-core/src/metadata/ directory (~1886 lines)

Acceptance criteria

• All metadata read operations use meedya_metadata::tag_io::extract_tags
• All metadata write operations use meedya_metadata::tag_io::write_tags
• Cover art operations use meedya_metadata::tag_io::{extract_cover_art, embed_cover_art}
• Tag name constants come from meedya_metadata::tag_registry::tags::*
• Tag registry uses meedya_metadata::tag_registry::DEFAULT_REGISTRY or custom TagRegistry::from_toml()
• mm-core/src/metadata/ removed (~1886 lines)
• Audio format support expanded (MP4 + ID3v2 + Vorbis + APE + RIFF via lofty)
• All metadata-related tests pass

Dependencies

• Blocked by: issue M2-UI-01: Scaffold Cross-Platform GUI #4 (Cargo dependency)
• MWBMPartners/MeedyaSuite-core meedya-metadata crate