Add Last.fm Recommendations music provider

[OzGav]

A new music provider that generates recommendation folders using the Last.fm API. Recommendations are resolved to playable items via streaming providers (Spotify, etc).

Recommendation Rows

The provider generates up to 9 recommendation folders, arranged into four groups configurable via toggle:

Personalized (based on user's MA library play counts)

• Discover Similar Artists: Top 5 most-played artists → 3 similar each → dedupe → first 10
• Discover Similar Tracks: Top 5 most-played tracks → 3 similar each → dedupe → first 10

Global Charts (Last.fm worldwide data)

• Global Top Artists: Request 15 → resolve → dedupe → first 10
• Global Top Tracks: Request 15 → resolve → dedupe → first 10

Genre-based (requires Last.fm username)

• Discover {Genre} Artists: User's top tag → 30 artists → filter library → top 3 + random 12 → resolve → first 10
• Discover {Genre} Albums: User's top tag → 30 albums → filter library → top 3 + random 12 → resolve → first 10
• Discover {Genre} Tracks: User's top tag → 30 tracks → filter library → top 3 + random 12 → resolve → first 10

Geographic (configurable country)

• Top Artists in {Country}: Request 15 → resolve → dedupe → first 10
• Top Tracks in {Country}: Request 15 → resolve → dedupe → first 10

Resolution Pipeline

1. Last.fm API returns artist/track/album names with optional MusicBrainz IDs (MBIDs)
2. For tracks: MBID → MusicBrainz API → ISRC lookup
3. Search streaming providers by ISRC (preferred) or name+artist fallback
4. Results cached at two levels: in-memory (session) and persistent (90 days)

Key Features

• All recommendation groups are disabled by default (user enables what they want)
• Configurable refresh interval (default 6 hours)
• 20-second startup delay to allow streaming providers to load first
• Genre rows use "top 3 + random sample" strategy with daily seed for variety
• Library items filtered from genre recommendations to surface new music
• Refresh Now button in advanced settings for manual refresh

[github-actions]

🔒 Dependency Security Report

✅ No dependency changes detected in this PR.

[marcelveldt]

I keep forgetting to come back on this one.
What we want is that metadata providers can also provide recommendations.

Long term goal is that we can have provider independent recommendations providers.
Based on services like listenbrainz, lastfm and ofcourse... AI

Now question is if this belongs to metadata providers or this should be plugins.
It definitely does not belong to the normal music providers as these providers do not provide music/audio on their own, they provide recommendations based on what you already have.

Also metadata is strictly about metadata so I'm inclined to say this should be plugin.
What do you think @OzGav ?

[OzGav]

As discussed on Discord. Changed to a metadata provider.