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/home/recentlyplayed.py

@@ -0,0 +1,35 @@
+from datetime import datetime
+
+from swingmusic.db.userdata import ScrobbleTable
+from swingmusic.models.playlist import Playlist
+from swingmusic.lib.playlistlib import get_first_4_images
+from swingmusic.utils.dates import (
+    create_new_date,
+    date_string_to_time_passed,
+)
+
+from swingmusic.store.tracks import TrackStore
+
+
+def get_recently_played_playlist(limit: int = 100):
+    playlist = Playlist(
+        id="recentlyplayed",
+        name="Recently Played",
+        image=None,
+        last_updated="Now",
+        settings={},
+        trackhashes=[],
+    )
+
+    scrobbles = ScrobbleTable.get_all(None, 100)
+    tracks = TrackStore.get_tracks_by_trackhashes(
+        [scrobble.trackhash for scrobble in scrobbles]
+    )
+
+    date = datetime.fromtimestamp(tracks[0].lastplayed)
+    playlist._last_updated = date_string_to_time_passed(create_new_date(date))
+
+    images = get_first_4_images(tracks=tracks)
+    playlist.images = images
+
+    return playlist, tracks