FIX: 6 lỗi âm thanh/Carla/temp-save/Ctrl-S/FX Chain Carla bridge

- Soundfont preview: hủy note đang chờ load soundfont (stopNote/stopAll/panic) — hết âm loop không dừng với MIDI Keyboard; preview dùng channel riêng (applyAITrackInstrument) — hết sai instrument
- Carla bridge: endpoint /carla-stop (all-notes-off OSC + terminate process) + stopBridge() khi track chuyển VSTi -> soundfont — hết âm play qua Carla cũ
- MIDI items play qua Carla khi VSTi loaded: scheduleCarlaNote route vào startTrackPlayback + startLocalTrackPlayback + ghost notes
- Tự động lưu temp khi tắt app: beforeunload/pagehide sendBeacon + autosave 30s + ghi storage/temp/autosave.json + khôi phục khi load lại
- Ctrl-S: desktop -> save-to-disk (Documents/SonicForgeDAW/Projects); docker -> Cloud/local
- FX Chain (Mastering + FX Rack): module Carla Bridge (VST FX) — load/openInCarla + stop/unload, pass-through trong graph

app/static/js/services/api.js

@@ -76,6 +76,9 @@ window.API_BASE_URL = window.API_BASE_URL || window.location.origin;
         setCarlaPath: (path) => apiRequest('/api/v1/system/carla-path', { method: 'POST', body: JSON.stringify({ carla_path: path }) }),
         // Mở native GUI VSTi trong Carla (chỉ khi runtime=desktop + có Carla local)
         openInCarla: (pluginName, pluginPath) => apiRequest('/api/v1/plugins/open-in-carla', { method: 'POST', body: JSON.stringify({ plugin_name: pluginName, plugin_path: pluginPath }) }),
+        // Unload Carla bridge: tắt mọi note đang ngân + terminate tiến trình Carla
+        // do app spawn (gọi khi track chuyển từ VSTi sang instrument soundfont)
+        stopCarla: () => apiRequest('/api/v1/plugins/carla-stop', { method: 'POST', body: JSON.stringify({}) }),
         // Gửi MIDI note (track ARM → Carla OSC) để preview VSTi realtime
         carlaMidi: (payload) => apiRequest('/api/v1/plugins/carla-midi', { method: 'POST', body: JSON.stringify(payload) }),
         // Quick-render preview VSTi (âm thật = âm export, cùng code path)
@@ -109,6 +112,9 @@ window.API_BASE_URL = window.API_BASE_URL || window.location.origin;
         cleanupBackups: (keep) => apiRequest('/api/v1/projects/cloud/backups/cleanup', { method: 'POST', body: JSON.stringify({ keep }) }),
 
         renderProject: (projectJson, outputFilename) => apiRequest('/api/v1/plugins/render', { method: 'POST', body: JSON.stringify({ project_json: projectJson, output_filename: outputFilename }) }),
+        // Ctrl-S desktop: lưu project ra THƯ MỤC CỦA HỆ ĐIỀU HÀNH
+        // (Documents/SonicForgeDAW/Projects — Windows; ~/SonicForgeDAW/Projects — Linux)
+        saveProjectToDisk: (name, dataJson) => apiRequest('/api/v1/projects/save-to-disk', { method: 'POST', body: JSON.stringify({ name, data_json: dataJson }) }),
         deleteSoundFont: (sfId) => apiRequest(`/api/v1/plugins/soundfont/${sfId}`, { method: 'DELETE' }),
         uploadSoundFont: async (file) => {
             const formData = new FormData();