plugin: fix OFX host property-suite gaps that purple-framed real plugins

Real plugins (CImg ChromaKeyerOFX, AddOFX) failed the render action with
kOfxStatFailed / MissingHostFeature and painted the magenta failure frame:

- images lacked the mandatory ImageBase properties (OfxPropType,
  PixelAspectRatio, PreMultiplication, Field, RenderScale); the ofxs
  ImageBase constructor throws on the missing/invalid strong reads
- PreMultiplication used the made-up string "OfxImagePreMultiplied";
  kOfxImagePreMultiplied is actually "OfxImageAlphaPremultiplied", the
  only value mapStrToPreMultiplicationEnum accepts (lldb __cxa_throw
  backtrace pinpointed this)
- RenderWindow is Int x4 per ofxsPropertyValidation, not Double x4
- field strings use the real constant "OfxFieldNone"
- clips define OfxImageClipPropConnected (isConnected is a strong read;
  optional mask clips blew up without it)
- choice params predefine empty ChoiceEnum / ChoiceLabelOption arrays
- isIdentity failure is no longer fatal (the C++ plugin renderer never
  calls it; plugins that error on it simply render normally)
- property suite coerces Int <-> Double on reads (the CImg framework
  reads the render window with propGetIntN against a Double store)
- in-args carry NatronOfxPropNativeOverlays=0 for the Natron framework
- plugin jobs pass a GL-kind marker so GL-only plugins take the real
  gl_bridge offscreen path instead of the CPU MissingHostFeature path
- trace-gated [ofx] diagnostics for property misses and suite calls

Verified with new smoke tests that render the real AddOFX and
ChromaKeyerOFX plugins through the executor and assert the output is
not the purple failure frame.

crates/oak-plugin/src/node_factory.rs

@@ -899,7 +899,11 @@ fn execute_plugin_job(
 		effect_input_id: effect_input_id.clone(),
 		inputs: inputs.clone(),
 		values: pod_values,
-		renderer: None,
+		// GL 渲染路径：OpenGL-only 插件（CImg 套件）在 CPU 路径的
+		// isIdentity 直接回 kOfxStatErrMissingHostFeature（紫帧根因）。
+		// 标记上下文只服务于 use_opengl 的 kind 判定；真正的 GL 渲染走
+		// gl_bridge 的离屏上下文（无头的 oak-worker 进程同样可用）。
+		renderer: Some(std::sync::Arc::new(crate::render::GlKindMarker)),
 		clear_destination: false,
 		interactive: false,
 	};
@@ -1129,6 +1133,76 @@ mod tests {
 		assert!(shared_plugin_instance("com.example.definitely-missing").is_none());
 	}
 
+	/// 最简单的真实插件（AddOFX：每个像素加一个常量）经 executor
+	/// 路径渲染成功——区分"系统性宿主问题"与"单插件问题"（机器上
+	/// 没装该插件则跳过）。
+	#[test]
+	fn add_plugin_renders_through_the_executor() {
+		render_real_plugin_smoke("net.sf.openfx.AddPlugin");
+	}
+
+	/// 真实 GL-only 插件（CImg 的 ChromaKeyerOFX）经 executor 路径渲染
+	/// 成功——GL-kind 标记必须把它引上可用的 GL 路径，而不是
+	/// MissingHostFeature 紫帧（机器上没装该插件则跳过）。
+	#[test]
+	fn cimg_chromakeyer_renders_through_the_executor() {
+		render_real_plugin_smoke("net.sf.openfx.ChromaKeyerPlugin");
+	}
+
+	fn render_real_plugin_smoke(identifier: &str) {
+		let host = crate::host::Host::global();
+		let _ = host.cache.scan();
+		if host.cache.find(identifier).is_none() {
+			eprintln!("{identifier} not installed; skipping");
+			return;
+		}
+		install_render_executor();
+		let instance = shared_plugin_instance(identifier)
+			.expect("the shared instance factory resolves the plugin");
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			let inst = instance_from_id(instance).expect("registered");
+			let props = &inst.value.plugin.descriptor.props;
+			props.with_locked(|all| {
+				for p in all.iter().filter(|p| p.name.contains("GL") || p.name.contains("OpenGL")) {
+					eprintln!("[probe] desc prop {} = {:?}", p.name, p.values);
+				}
+			});
+		}
+
+		// 8x8 不透明绿帧（典型 keyer 输入）。
+		let mut frame = oak_render::eval::generate_frame(
+			oak_core::Rational::new(0, 1),
+			(8, 8),
+			oak_core::PixelFormat::F32,
+		)
+		.unwrap();
+		for px in frame.data.chunks_exact_mut(16) {
+			for (c, v) in px.chunks_exact_mut(4).zip([0.1f32, 0.9, 0.1, 1.0]) {
+				c.copy_from_slice(&v.to_le_bytes());
+			}
+		}
+		let spec = oak_render::eval::JobSpec::Plugin {
+			instance,
+			time: 0.0,
+			effect_input_id: Some("Source".to_string()),
+			inputs: Vec::new(),
+			values: Vec::new(),
+		};
+		let out = execute_plugin_job(&oak_render::eval::PluginJobRequest {
+			spec: &spec,
+			src: oak_render::texture::Texture::wrap_frame(frame),
+		})
+		.expect("the GL-capable render succeeds (no MissingHostFeature purple)");
+		let oak_render::texture::Texture::Cpu(out_frame) = &out else {
+			panic!("a CPU frame comes back");
+		};
+		let mut px = [0f32; 4];
+		for i in 0..4 {
+			px[i] = f32::from_le_bytes(out_frame.data[i * 4..i * 4 + 4].try_into().unwrap());
+		}
+		assert_ne!(px, [1.0, 0.0, 1.0, 1.0], "must not be the purple failure frame");
+	}
+
 	/// 构造一个只含 push-button 参数的最小实例（直接登记进注册表）。
 	fn instance_with_push_button() -> u64 {
 		use std::ffi::{c_char, c_void};