Move backend files to root level for cleaner GitHub display

- Move all backend files from swingmusic/ to root level
- Backend files now display directly on GitHub repository page
- Keep client applications as submodules (swingmusic-android, swingmusic-desktop, swingmusic-webclient)
- Update README to reflect new structure (no cd swingmusic needed)
- Cleaner, more professional GitHub repository layout

Files moved to root:
- src/ (main source code)
- pyproject.toml, requirements.txt, run.py
- swingmusic.spec, uv.lock, version.txt
- services/

Result: GitHub shows backend files directly while maintaining organized structure

src/swingmusic/lib/index.py

@@ -0,0 +1,43 @@
+import gc
+import logging
+from time import time
+from swingmusic.lib.mapstuff import (
+    map_album_colors,
+    map_artist_colors,
+    map_favorites,
+    map_scrobble_data,
+)
+from swingmusic.lib.populate import CordinateMedia
+from swingmusic.lib.recipes.recents import RecentlyAdded
+from swingmusic.lib.tagger import IndexTracks
+from swingmusic.store.albums import AlbumStore
+from swingmusic.store.artists import ArtistStore
+from swingmusic.store.folder import FolderStore
+from swingmusic.store.tracks import TrackStore
+from swingmusic.utils.threading import background
+
+log = logging.getLogger(__name__)
+
+@background
+def index_everything():
+    IndexTracks()
+
+    key = str(time())
+    TrackStore.load_all_tracks(key)
+    AlbumStore.load_albums(key)
+    ArtistStore.load_artists(key)
+    FolderStore.load_filepaths()
+
+    # NOTE: Rebuild recently added items on the homepage store
+    RecentlyAdded()
+
+    # map colors
+    map_album_colors()
+    map_artist_colors()
+
+    map_scrobble_data()
+    map_favorites()
+
+    CordinateMedia(instance_key=str(time()))
+    gc.collect()
+    log.info("Indexing completed")