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

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

Let me provide the SEARCH/REPLACE blocks.carla.h

@@ -0,0 +1,83 @@
+#ifndef CARLA_H
+#define CARLA_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <jack/jack.h>
+
+// Carla plugin types we support
+typedef enum {
+    PLUGIN_TYPE_NONE,
+    PLUGIN_TYPE_LV2,
+    PLUGIN_TYPE_VST2,
+    PLUGIN_TYPE_VST3,
+    PLUGIN_TYPE_CLAP,
+    PLUGIN_TYPE_INTERNAL  // Our built-in plugins (gain, etc.)
+} PluginType;
+
+// Plugin descriptor
+typedef struct {
+    char name[256];
+    char uri[512];
+    PluginType type;
+    int carla_plugin_id;  // Carla's internal plugin ID
+    int num_parameters;
+    float *parameters;    // Current parameter values
+    char **parameter_names;
+} PluginInfo;
+
+// Rack for a single channel
+typedef struct {
+    int num_plugins;
+    PluginInfo plugins[16];  // Max 16 plugins per channel
+    float volume;            // Channel volume (0.0 - 2.0)
+    bool bypassed;
+} ChannelRack;
+
+// Carla host state
+typedef struct {
+    bool initialized;
+    ChannelRack channel_racks[8];  // One rack per channel (MAX_CHANNELS)
+    jack_client_t *client;
+    // For plugin scanning
+    char **available_plugins;
+    int num_available_plugins;
+} CarlaHost;
+
+// Initialize Carla host
+int carla_init(CarlaHost *host, jack_client_t *client);
+
+// Cleanup Carla host
+void carla_cleanup(CarlaHost *host);
+
+// Add a plugin to a channel's rack
+int carla_add_plugin(CarlaHost *host, int channel, const char *uri, PluginType type);
+
+// Remove a plugin from a channel's rack
+int carla_remove_plugin(CarlaHost *host, int channel, int plugin_index);
+
+// Set plugin parameter
+int carla_set_parameter(CarlaHost *host, int channel, int plugin_index, int param_index, float value);
+
+// Get plugin parameter
+float carla_get_parameter(CarlaHost *host, int channel, int plugin_index, int param_index);
+
+// Set channel volume
+void carla_set_channel_volume(CarlaHost *host, int channel, float volume);
+
+// Get channel volume
+float carla_get_channel_volume(CarlaHost *host, int channel);
+
+// Process audio through the rack (called from audio thread)
+void carla_process(CarlaHost *host, int channel, float *in_buffer, float *out_buffer, jack_nframes_t nframes);
+
+// Scan for available plugins
+int carla_scan_plugins(CarlaHost *host);
+
+// Get available plugin names for fuzzy search
+const char** carla_get_available_plugins(CarlaHost *host, int *count);
+
+// Get plugin display name
+const char* carla_get_plugin_name(CarlaHost *host, int channel, int plugin_index);
+
+#endif // CARLA_H