M7-M16: VST FX GUI native embed hoàn thiện — fix click-2-lần chuyển slot, anchor lần mở đầu, taskbar icon

- app.jsx: masterGuiOpenRef sync truoc setState — guard chuyen slot doc ref, het race closure (click 1 lan chuyen slot)
- JuceFxGuiHost.cpp: M14 applyAnchor truoc setVisible (het flash giua man hinh); M15 clear WS_EX_APPWINDOW + set TOOLWINDOW (het taskbar icon — JUCE set APPWINDOW 0x40000 thang TOOLWINDOW); M9 owner DAW + M9d skip applyOwner khi an
- JuceFxLoop.cpp: M16 bo clearAnchor khi ed.open (retry ed.open ~700ms xoa rect fresh -> window moi khong anchor duoc lan dau mo panel); chi clear khi Close
- JuceFxEngine/app.jsx/plugins.py/fx_realtime.py: editor session realtime, anchor rect routing, retry ed.open
- Rebuild engine PyInstaller + juce_fx_bridge cmake; binaries dong bo 5 noi (bridge 7464a7ef)

app/static/js/services/api.js

@@ -96,6 +96,8 @@ window.API_BASE_URL = (window.API_BASE_URL || window.location.origin).replace(/\
         closeFxGui: (payload) => apiRequest('/api/v1/plugins/fx-gui/close', { method: 'POST', body: JSON.stringify(payload) }),
         hideFxGui: (payload) => apiRequest('/api/v1/plugins/fx-gui/hide', { method: 'POST', body: JSON.stringify(payload) }),
         showFxGui: (payload) => apiRequest('/api/v1/plugins/fx-gui/show', { method: 'POST', body: JSON.stringify(payload) }),
+        // M7: anchor GUI native vào rect panel (px màn hình vật lý) — C++ SetWindowPos khi rect đổi
+        rectFxGui: (payload) => apiRequest('/api/v1/plugins/fx-gui/rect', { method: 'POST', body: JSON.stringify(payload) }),
         soundfontRender: (payload) => apiRequest('/api/v1/plugins/soundfont-render', { method: 'POST', body: JSON.stringify(payload) }),
         // Thư viện preset VST3 (.vstpreset) — cầu nối preset → pedalboard
         listPresets: () => apiRequest('/api/v1/presets', { method: 'GET' }),