Fix crash: Move plugin scan into Processor (survives editor close), use safe async callback

Source/PluginBridgeProcessor.h

@@ -37,18 +37,29 @@ public:
     void getStateInformation(juce::MemoryBlock& destData) override;
     void setStateInformation(const void* data, int sizeInBytes) override;
 
-    // Public access for Editor and McpServer
+    // Public access
     bool isMcpServerRunning() const;
     int getMcpServerPort() const;
     HostedPluginManager& getHostedPluginManager() { return hostManager; }
 
-    // Load plugin from GUI (called on message thread)
+    // Load plugin (called on message thread)
     void loadPluginFromFile(const juce::File& file);
 
+    // Plugin scanning (owned by Processor — safe lifetime)
+    void startPluginScan();
+    bool isScanComplete() const { return scanComplete; }
+    bool isScanning() const { return scanning; }
+    const juce::Array<juce::PluginDescription>& getScannedPlugins() const { return scannedPlugins; }
+
 private:
     HostedPluginManager hostManager;
     McpServer mcpServer;
     static constexpr int kDefaultMcpPort = 16620;
 
+    // Plugin scan state (lives in Processor — safe)
+    juce::Array<juce::PluginDescription> scannedPlugins;
+    std::atomic<bool> scanComplete{false};
+    std::atomic<bool> scanning{false};
+
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(PluginBridgeProcessor)
 };