feat(oakplugin): GL render bridge, color picker, push-button action, worker progress, Interact host

- gl_bridge: macOS CGL offscreen context (process-wide singleton,
  serialized GlGuard), real GL output textures/FBOs, glReadPixels
  readback with vertical flip and format conversion; use_opengl now
  really engages for OpenGLRenderSupported plugins (verified with real
  GL rendering: C smoke 11/11, unit tests, GL e2e).
- OfxColor: color params get a swatch button plus a real picker popup
  (RGBA sliders, live preview, hex input, undoable commit) replacing
  the four spinboxes.
- Push buttons route kOfxActionInstanceChanged (UserEdited) per the
  OFX contract; test plugin asserts the callback.
- Worker-side plugin progress flows to the main-process progress
  dialog over the NDJSON control channel, with cancel propagation.
- OFX Interact host: NewInteract/Describe lifecycle, Draw/Pen/Key/Idle
  action surface with proper in-args, DrawSuite v1 host implementation
  sharing the gl_bridge context; interact test plugin verifies the
  event stream and real GL drawing.

crates/oakplugin/src/progress.rs

@@ -39,6 +39,9 @@ use std::sync::{Arc, Mutex, OnceLock};
 pub trait UiProgressReporter: Send {
 	/// 上报进度（0.0..=1.0）；false = 取消。
 	fn update(&mut self, progress: f64) -> bool;
+	/// progressEnd 通知（默认 no-op；app 可据此关闭进度 UI / 把完成
+	/// 事件转发过 IPC——worker 侧的进度回传依赖它）。
+	fn end(&mut self) {}
 }
 
 /// 报告器工厂：progressStart 携 (label, message) 调用，现造一个
@@ -160,4 +163,12 @@ impl ProgressReporter {
 	pub(crate) fn is_cancelled(&self) -> bool {
 		self.cancelled.load(Ordering::Relaxed)
 	}
+
+	/// progressEnd 钩子：转发给 UI 报告器（无报告器时 no-op）。
+	pub(crate) fn end_ui(&self) {
+		let mut slot = self.ui.lock().unwrap_or_else(|e| e.into_inner());
+		if let Some(ui) = slot.as_mut() {
+			ui.end();
+		}
+	}
 }