feat: integrate Carla plugin host with rack view, fuzzy search, and volume control

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

dispatcher.h

@@ -6,6 +6,7 @@
 #include <stdatomic.h>
 #include <jack/jack.h>
 #include <pthread.h>
+#include "carla.h"
 
 // ============================================================
 // Application State - contains ALL application state
@@ -82,6 +83,9 @@ typedef struct {
         size_t prev_read_positions[MAX_UNDO_HISTORY];
     } undo;
     
+    // Carla host
+    CarlaHost carla_host;
+    
     // JACK info (needed by audio thread)
     jack_nframes_t sample_rate;
     bool running;
@@ -110,6 +114,11 @@ typedef enum {
     ACTION_LOAD_CLIP,
     ACTION_MIDI_NOTE_ON,
     ACTION_MIDI_SCENE_LAUNCH,
+    ACTION_RACK_ADD_PLUGIN,
+    ACTION_RACK_REMOVE_PLUGIN,
+    ACTION_RACK_SET_PARAMETER,
+    ACTION_RACK_SET_VOLUME,
+    ACTION_RACK_BYPASS,
     ACTION_PROCESS_AUDIO,
     ACTION_QUIT
 } ActionType;
@@ -128,6 +137,11 @@ typedef struct {
         struct { int clip_index; char filename[256]; } load_clip;
         struct { int note; int velocity; int channel; jack_nframes_t time; } midi_note_on;
         struct { int scene_index; jack_nframes_t time; } midi_scene_launch;
+        struct { int channel; char uri[512]; PluginType type; } rack_add_plugin;
+        struct { int channel; int plugin_index; } rack_remove_plugin;
+        struct { int channel; int plugin_index; int param_index; float value; } rack_set_parameter;
+        struct { int channel; float volume; } rack_set_volume;
+        struct { int channel; bool bypass; } rack_bypass;
         struct { jack_nframes_t nframes; } process_audio;
     } data;
 } Action;