Dock: LAYERS opens its pallet like Insert Block, Layer Manager layout fixes, 150 ms auto-hide hover delay

- LAYERS ribbon button runs a command that opens the Layer Manager pallet;
  the ribbon no longer keeps it highlighted.
- Layer Manager: search box stays right-aligned, the column header fills
  the row, no stray contour lines when the pallet is taller than its rows.
- Auto-hidden edges don't show the shown-group accent bar.
- Auto-hide reveal and hide wait 150 ms of rest, so passing over the
  strip doesn't flash groups open.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013RyGiMXcsf9HTKfqDxaQGt

src/app/commands/fileops.rs

@@ -354,7 +354,9 @@ impl OpenCADStudio {
             "ORTHO" => return Some(Task::done(Message::ToggleOrtho)),
             "PARALLEL" => return Some(Task::done(Message::SetProjection(true))),
             "PERSP" => return Some(Task::done(Message::SetProjection(false))),
-            "LAYERS" => return Some(Task::done(Message::ToggleLayers)),
+            // LAYERS opens the Layer Manager pallet (its close button or
+            // the toggle message close it).
+            "LAYERS" => self.open_layers_pallet(),
 
             // SCRIPT <path> — run a command script: each non-comment
             // line is fed through the same command path the `--script` startup