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/api/plugins/__init__.py

@@ -0,0 +1,103 @@
+from flask_openapi3 import Tag
+from flask_openapi3 import APIBlueprint
+from pydantic import BaseModel, Field
+from swingmusic.api.auth import admin_required
+from swingmusic.config import UserConfig
+from swingmusic.db.userdata import PluginTable
+from swingmusic.plugins.lastfm import LastFmPlugin
+from swingmusic.utils.auth import get_current_userid
+
+bp_tag = Tag(name="Plugins", description="Manage plugins")
+api = APIBlueprint("plugins", __name__, url_prefix="/plugins", abp_tags=[bp_tag])
+
+
+@api.get("/")
+def get_all_plugins():
+    """
+    List all plugins
+    """
+    plugins = PluginTable.get_all()
+    return {"plugins": plugins}
+
+
+class PluginBody(BaseModel):
+    plugin: str = Field(description="The plugin name", example="lyrics")
+
+
+class PluginActivateBody(PluginBody):
+    active: bool = Field(
+        description="New plugin active state", example=False, default=False
+    )
+
+
+@api.post("/setactive")
+@admin_required()
+def activate_deactivate_plugin(body: PluginActivateBody):
+    """
+    Activate/Deactivate plugin
+    """
+    name = body.plugin
+    PluginTable.activate(name, body.active)
+
+    return {"message": "OK"}, 200
+
+
+class PluginSettingsBody(PluginBody):
+    settings: dict = Field(
+        description="The new plugin settings", example={"key": "value"}
+    )
+
+
+@api.post("/settings")
+@admin_required()
+def update_plugin_settings(body: PluginSettingsBody):
+    """
+    Update plugin settings
+    """
+    plugin = body.plugin
+    settings = body.settings
+
+    if not plugin or not settings:
+        return {"error": "Missing plugin or settings"}, 400
+
+    PluginTable.update_settings(plugin, settings)
+    plugin = PluginTable.get_by_name(plugin)
+
+    return {"status": "success", "settings": plugin.settings}
+
+
+class LastFmSessionBody(BaseModel):
+    token: str = Field(description="The token to use to create the session")
+
+
+@api.post("/lastfm/session/create")
+def create_lastfm_session(body: LastFmSessionBody):
+    """
+    Create a Last.fm session
+    """
+    if not body.token:
+        return {"error": "Missing token"}, 400
+
+    lastfm = LastFmPlugin(current_userid=get_current_userid())
+    session_key = lastfm.get_session_key(body.token)
+
+    if session_key:
+        config = UserConfig()
+        current_user = get_current_userid()
+        config.lastfmSessionKeys[str(current_user)] = session_key
+        config.lastfmSessionKeys = config.lastfmSessionKeys
+
+    return {"status": "success", "session_key": session_key}
+
+
+@api.post("/lastfm/session/delete")
+def delete_lastfm_session():
+    """
+    Delete the Last.fm session
+    """
+    config = UserConfig()
+    current_user = get_current_userid()
+    config.lastfmSessionKeys[str(current_user)] = ""
+    config.lastfmSessionKeys = config.lastfmSessionKeys
+
+    return {"status": "success"}