phase5: mặc định RENDER_ENGINE=bridge, gỡ pedalboard khỏi requirements/source/LICENSE

- config.py: SF_RENDER_ENGINE default 'bridge' (pedalboard GPL-3.0 đã gỡ)
- requirements.txt: bỏ pedalboard==0.9.19
- vst_engine.py: bỏ HAS_PEDALBOARD/check_pedalboard_safe/load_vst/import pedalboard;
  midi_events_to_messages giữ làm utility thuần (không gate pedalboard)
- render_engine.py: bỏ nhánh elif vst and HAS_PEDALBOARD + import thừa
- plugins.py: preview/midi-render chỉ qua native_bridge; guard SF_RENDER_ENGINE=bridge
- runtime.py: _vst_render_available() check bridge exe (SF_BRIDGE_PATH/install/) thay find_spec('pedalboard')
- LICENSE.md/THIRD_PARTY_LICENSES.md: bỏ cảnh báo GPL-3.0 pedalboard, đánh số lại
- tests: bỏ test golden so pedalboard + test requires_pedalboard; 114 passed 0 skip

tests/test_render_engine.py

@@ -56,8 +56,8 @@ def test_render_session_vsti_bridge_unknown_instrument_falls_back(monkeypatch):
     assert (buf != 0.0).any()
 
 
-def test_render_session_vsti_pedalboard_default_falls_back(monkeypatch):
-    """Mặc định pedalboard: không có plugin load được → oscillator (không crash)."""
+def test_render_session_vsti_non_bridge_engine_falls_back(monkeypatch):
+    """Engine không phải bridge (vd 'pedalboard' cũ): VSTi → fallback oscillator (không crash)."""
     from app.api.v1 import plugins as pl
     monkeypatch.setattr(pl.settings, "RENDER_ENGINE", "pedalboard")
     engine = PythonRenderEngine()
@@ -69,7 +69,7 @@ def test_render_session_vsti_pedalboard_default_falls_back(monkeypatch):
 def test_render_session_fx_chorus_scipy_fallback():
     """FX chorus: fallback scipy (không pedalboard) không crash, thay đổi âm."""
     from app.api.v1 import plugins as pl
-    pl.settings.RENDER_ENGINE = "pedalboard"
+    pl.settings.RENDER_ENGINE = "bridge"
     engine = PythonRenderEngine()
     session = {"tracks": [_midi_track("__no_such_plugin__", fx_type="chorus")]}
     buf = engine.render_session_container(session, {}, 120.0, 4, 44100)
@@ -80,7 +80,7 @@ def test_render_session_fx_chorus_scipy_fallback():
 def test_render_session_fx_reverb_scipy_fallback():
     """FX reverb: fallback scipy (không pedalboard) không crash, thay đổi âm."""
     from app.api.v1 import plugins as pl
-    pl.settings.RENDER_ENGINE = "pedalboard"
+    pl.settings.RENDER_ENGINE = "bridge"
     engine = PythonRenderEngine()
     session = {"tracks": [_midi_track("__no_such_plugin__", fx_type="reverb")]}
     buf = engine.render_session_container(session, {}, 120.0, 4, 44100)