Checkpoint 2: integrate native Editor, MCP, gameplay builds and standalone export

include/faset/editor/plugins.hpp

@@ -0,0 +1,24 @@
+#pragma once
+#include <faset/editor/commands.hpp>
+#include <functional>
+#include <memory>
+namespace faset::editor {
+class PluginManager {
+  public:
+    using Logger = std::function<void(std::string)>;
+    explicit PluginManager(Commands&, Logger);
+    ~PluginManager();
+    PluginManager(const PluginManager&) = delete;
+    PluginManager& operator=(const PluginManager&) = delete;
+    // Discover and validate the complete dependency graph before loading code.
+    // Individual failures are reported; dependents are never loaded after one.
+    void load(const std::filesystem::path& directory);
+    Json status() const;
+    Json panels() const;
+    static std::string fingerprint();
+
+  private:
+    struct Impl;
+    std::unique_ptr<Impl> impl_;
+};
+} // namespace faset::editor