Reorganize repository structure for better organization

- Move backend code to swingmusic/ folder
- Move client applications to root level (swingmusic-android, swingmusic-desktop, swingmusic-webclient)
- Remove intermediate backend/ and clients/ folders
- Update README with new folder structure and setup instructions
- Clean and organized repository layout

src/swingmusic/api/plugins/lyrics.py

@@ -1,64 +0,0 @@
-from flask_openapi3 import Tag
-from flask_openapi3 import APIBlueprint
-from pydantic import Field
-from swingmusic.api.apischemas import TrackHashSchema
-from swingmusic.lib.lyrics import Lyrics as Lyrics_class
-
-from swingmusic.plugins.lyrics import Lyrics
-from swingmusic.settings import Defaults
-from swingmusic.utils.hashing import create_hash
-
-bp_tag = Tag(name="Lyrics Plugin", description="Musixmatch lyrics plugin")
-api = APIBlueprint(
-    "lyricsplugin", __name__, url_prefix="/plugins/lyrics", abp_tags=[bp_tag]
-)
-
-
-class LyricsSearchBody(TrackHashSchema):
-    title: str = Field(description="The track title ", example=Defaults.API_TRACKNAME)
-    artist: str = Field(description="The track artist ", example=Defaults.API_ARTISTNAME)
-    album: str = Field(description="The track track album ", example=Defaults.API_ALBUMNAME)
-    filepath: str = Field(
-        description="Track filepath to save the lyrics file relative to",
-        example="/home/cwilvx/temp/crazy song.mp3",
-    )
-
-
-@api.post("/search")
-def search_lyrics(body: LyricsSearchBody):
-    """
-    Search for lyrics by title and artist
-    """
-    title = body.title
-    artist = body.artist
-    album = body.album
-    filepath = body.filepath
-    trackhash = body.trackhash
-
-    finder = Lyrics()
-    data = finder.search_lyrics_by_title_and_artist(title, artist)
-
-    if not data:
-        return {"trackhash": trackhash, "lyrics": None}
-
-    perfect_match = data[0]
-
-    for track in data:
-        i_title = track["title"]
-        i_album = track["album"]
-
-        if create_hash(i_title) == create_hash(title) and create_hash(i_album) == create_hash(album):
-            perfect_match = track
-
-    track_id = perfect_match["track_id"]
-    lrc = finder.download_lyrics(track_id, filepath)
-
-    if lrc is not None:
-        lyrics = Lyrics_class(lrc)
-        if lyrics.is_synced:
-            formatted_lyrics = lyrics.format_synced_lyrics()
-        else:
-            formatted_lyrics = lyrics.format_unsynced_lyrics()
-        return {"trackhash": trackhash, "lyrics": formatted_lyrics, "synced": lyrics.is_synced}, 200
-
-    return {"trackhash": trackhash, "lyrics": None, "synced": False}, 200