feat(providers): add a pluggable station-catalogue seam

The app now holds one RadioProvider and asks it for stations, song history and stream URLs instead of importing SomaFM's HTTP client directly.

- models.py: provider-neutral Song/Station plus the shared parsers every catalogue needs (Station.provider/.uid keep ids unique once there is more than one).
- providers/base.py: the RadioProvider interface and the toolkit it needs in practice - httpx client factory, .pls/.m3u resolution with an 8h disk cache, and a default stream_candidates() strategy.
- providers/somafm/: everything SomaFM-specific (channels.json, songs/<id>.json, PLS layout, guessed icecast mirrors) behind SomaFMProvider.
- providers/__init__.py: registry, get_provider() and --provider, remembered in the config file.

Widgets render branding, splash copy and the help credits from the active provider, so a second catalogue needs no UI changes; with SomaFM selected the screen is byte-identical to before.

tests/test_app.py

@@ -6,22 +6,31 @@ from datetime import datetime, timedelta, timezone
 
 import pytest
 
-from somafm_tui import config
-from somafm_tui.api import Song
-from somafm_tui.app import SomaFMApp
-from somafm_tui.widgets.help import HelpScreen
-from somafm_tui.widgets.stage import StagePanel
-from somafm_tui.widgets.station_list import StationList
+from beefy_player import config
+from beefy_player.app import BeefyPlayerApp
+from beefy_player.models import Song
+from beefy_player.widgets.help import HelpScreen
+from beefy_player.widgets.stage import StagePanel
+from beefy_player.widgets.station_list import StationList
 
 
-def rendered_text(app: SomaFMApp) -> str:
+def _history_method(func):
+    """Adapt a ``(client, station_id)`` fake to the provider method signature."""
+
+    async def method(self, client, station_id):
+        return await func(client, station_id)
+
+    return method
+
+
+def rendered_text(app: BeefyPlayerApp) -> str:
     svg = html.unescape(app.export_screenshot()).replace("\xa0", " ")
     return re.sub(r"<[^>]+>", " ", svg)
 
 
 @pytest.mark.asyncio
 async def test_boot_navigation_filter_favourite_visualizer_help() -> None:
-    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
     async with app.run_test(size=(110, 36)) as pilot:
         await pilot.pause()
 
@@ -92,7 +101,7 @@ async def test_boot_navigation_filter_favourite_visualizer_help() -> None:
 
 @pytest.mark.asyncio
 async def test_stage_renders_history_and_listener_count() -> None:
-    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
     async with app.run_test(size=(110, 40)) as pilot:
         await pilot.pause()
         station = app.current
@@ -123,9 +132,22 @@ async def test_stage_renders_history_and_listener_count() -> None:
             assert needle in text
 
 
+@pytest.mark.asyncio
+async def test_splash_names_the_provider() -> None:
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
+    async with app.run_test(size=(100, 32)) as pilot:
+        await pilot.pause()
+        app.current = None
+        app.query_one(StagePanel).refresh_stage()
+        await pilot.pause()
+        text = rendered_text(app)
+        assert "SOMA FM" in text
+        assert "somafm.com/channels.json" in text
+
+
 @pytest.mark.asyncio
 async def test_narrow_layout() -> None:
-    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
     async with app.run_test(size=(64, 20)) as pilot:
         await pilot.pause()
         app.query_one(StagePanel).refresh_stage()
@@ -138,7 +160,7 @@ async def test_narrow_layout() -> None:
 
 @pytest.mark.asyncio
 async def test_stage_shows_bandcamp_link_only_when_present() -> None:
-    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
     async with app.run_test(size=(110, 40)) as pilot:
         await pilot.pause()
         station = app.current
@@ -162,7 +184,7 @@ async def test_stage_shows_bandcamp_link_only_when_present() -> None:
 
 @pytest.mark.asyncio
 async def test_bandcamp_link_survives_history_refresh(monkeypatch) -> None:
-    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
     async with app.run_test(size=(110, 40)) as pilot:
         await pilot.pause()
         station = app.current
@@ -187,7 +209,9 @@ async def test_bandcamp_link_survives_history_refresh(monkeypatch) -> None:
                 )
             ]
 
-        monkeypatch.setattr("somafm_tui.app.api.fetch_history", fake_fetch_history)
+        monkeypatch.setattr(
+            type(app.provider), "fetch_history", _history_method(fake_fetch_history)
+        )
         worker = app._fetch_history(station.id)
         await worker.wait()
         await pilot.pause()
@@ -200,7 +224,7 @@ async def test_bandcamp_link_survives_history_refresh(monkeypatch) -> None:
 
 @pytest.mark.asyncio
 async def test_cached_bandcamp_link_is_reapplied_to_new_song() -> None:
-    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
     async with app.run_test(size=(110, 40)) as pilot:
         await pilot.pause()
         station = app.current
@@ -219,7 +243,7 @@ async def test_cached_bandcamp_link_is_reapplied_to_new_song() -> None:
 
 @pytest.mark.asyncio
 async def test_media_session_commands_drive_the_app() -> None:
-    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    app = BeefyPlayerApp(autoplay=False, offline=True, audio=False)
     async with app.run_test(size=(100, 30)) as pilot:
         await pilot.pause()
         # The status bar names whichever backend this platform uses.