Summary

This PR introduces a manual lyrics search flow when automatic lyrics lookup fails. Instead of showing an error state, users can now edit the song title and optionally the artist to manually search for lyrics.

Motivation

This change is motivated by real-world cases where song metadata is incomplete or incorrect (e.g. from yt-dlp), which makes automatic lyrics search fail even though lyrics are actually available.

Originally, this was intended to be implemented before the 0.5.0 beta release, as it fits the same UX theme of improving lyrics discovery. However, it should still integrate cleanly with the current flow and does not introduce breaking changes.

Flow

• Lyrics are initially fetched automatically using existing metadata (same as before).
• When no results are found, a Not Found state is shown instead of failing.
• Users are given the option to manually adjust the title and optional artist.
• The edited values are then used to perform a manual lyrics search.

Demo

This video demonstrates the manual lyrics search flow when automatic lyrics lookup fails:

Key changes

• Introduce NotFound state in lyrics search UI
• Show manual search dialog instead of error state
• Allow editable title and optional artist input

Fixes #699