fix: resizable, scrollable editor so all controls stay reachable

The global controls were one non-wrapping horizontal row that pushed Ceiling off
the right edge, and the window was fixed-size, so some controls (Ceiling, the full
'All' column) couldn't be reached. Wrapped the editor in a ResizableWindow, moved
the global controls into a vertical label|slider grid, and put everything in a
vertical ScrollArea. Placeholder layout still (Stage 6 replaces it), just usable.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib.rs

@@ -1,5 +1,10 @@
 use nih_plug::prelude::*;
-use nih_plug_egui::{create_egui_editor, egui, widgets, EguiState};
+use nih_plug_egui::{
+    create_egui_editor,
+    egui::{self, Vec2},
+    resizable_window::ResizableWindow,
+    widgets, EguiState,
+};
 use std::sync::Arc;
 
 mod dsp;
@@ -265,6 +270,7 @@ impl Plugin for Codename206 {
 
     fn editor(&mut self, _async_executor: AsyncExecutor<Self>) -> Option<Box<dyn Editor>> {
         let params = self.params.clone();
+        let egui_state = self.params.editor_state.clone();
         create_egui_editor(
             self.params.editor_state.clone(),
             (),
@@ -289,19 +295,30 @@ impl Plugin for Codename206 {
                     ui.add(widgets::ParamSlider::for_param(&p.bypass, setter));
                 };
 
-                egui::CentralPanel::default().show(egui_ctx, |ui| {
+                // Resizable window; vertical scroll so every control stays reachable even when the
+                // window is small. (Placeholder layout — Stage 6 will replace it.)
+                ResizableWindow::new("editor")
+                    .min_size(Vec2::new(480.0, 320.0))
+                    .show(egui_ctx, egui_state.as_ref(), |ui| {
+                        egui::ScrollArea::vertical().show(ui, |ui| {
                             ui.heading(Self::NAME);
-                    ui.horizontal(|ui| {
+                            // Global controls stacked vertically so they never overflow sideways.
+                            egui::Grid::new("globals").num_columns(2).show(ui, |ui| {
                                 ui.label("Xover Lo/Mid");
                                 ui.add(widgets::ParamSlider::for_param(&params.crossover_low_hz, setter));
+                                ui.end_row();
                                 ui.label("Xover Mid/Hi");
                                 ui.add(widgets::ParamSlider::for_param(&params.crossover_high_hz, setter));
+                                ui.end_row();
                                 ui.label("Look-ahead");
                                 ui.add(widgets::ParamSlider::for_param(&params.look_ahead_ms, setter));
+                                ui.end_row();
                                 ui.label("Ceiling");
                                 ui.add(widgets::ParamSlider::for_param(&params.output_ceiling_db, setter));
+                                ui.end_row();
                                 ui.label("Lim Release");
                                 ui.add(widgets::ParamSlider::for_param(&params.limiter_release_ms, setter));
+                                ui.end_row();
                             });
                             ui.separator();
                             ui.columns(4, |cols| {
@@ -311,6 +328,7 @@ impl Plugin for Codename206 {
                                 band_col(&mut cols[3], "ALL", &params.all);
                             });
                         });
+                    });
             },
         )
     }