Feat: viewport display lock, extended properties, VPLAYER and VPORTS commands

- Enforce status.locked in pan_active_viewport and zoom_active_viewport:
  locked viewports now reject pan/zoom inputs entirely
- Add perspective, render_mode, shade_plot_mode, hide_plot, ucs_icon_visible
  fields to the viewport property panel with appropriate pickers/toggles
- Add VPORTS command: lists all user viewports in the current layout
  (id, size, position, scale, on/locked state) in the command line
- Add VPLAYER command: per-viewport layer freeze/thaw from the command line
  (F <layer> to freeze, T <layer> to thaw, Enter to exit)
- Add CmdResult::VpLayerUpdate variant and its handler in apply_cmd_result

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/modules/layout/mod.rs

@@ -2,6 +2,7 @@
 // This tab is only shown when the active layout is not "Model".
 
 pub mod mview;
+pub mod vplayer;
 
 use crate::modules::{CadModule, IconKind, ModuleEvent, RibbonGroup, ToolDef};
 

src/modules/layout/vplayer.rs

@@ -0,0 +1,85 @@
+// VPLAYER — per-viewport layer freeze/thaw command.
+//
+// Usage (command line):
+//   VPLAYER
+//   > F <layer_name>   → freeze layer in active viewport
+//   > T <layer_name>   → thaw layer in active viewport
+//   > Enter            → exit
+//
+// Layer names are case-insensitive. Multiple space-separated names are accepted.
+
+use acadrust::Handle;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult};
+use crate::scene::wire_model::WireModel;
+
+pub struct VplayerCommand {
+    vp_handle: Handle,
+}
+
+impl VplayerCommand {
+    pub fn new(vp_handle: Handle) -> Self {
+        Self { vp_handle }
+    }
+}
+
+impl CadCommand for VplayerCommand {
+    fn name(&self) -> &'static str {
+        "VPLAYER"
+    }
+
+    fn prompt(&self) -> String {
+        "VPLAYER  F <layer> = Freeze  |  T <layer> = Thaw  |  Enter = Exit".to_string()
+    }
+
+    fn wants_text_input(&self) -> bool {
+        true
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        let text = text.trim();
+        if text.is_empty() {
+            return Some(CmdResult::Cancel);
+        }
+
+        let mut parts = text.splitn(2, char::is_whitespace);
+        let op = parts.next().unwrap_or("").to_uppercase();
+        let rest = parts.next().unwrap_or("").trim();
+
+        let layer_names: Vec<String> = rest
+            .split_whitespace()
+            .map(|s| s.to_string())
+            .collect();
+
+        if layer_names.is_empty() {
+            return None; // no layer name given — ignore and re-prompt
+        }
+
+        match op.as_str() {
+            "F" | "FREEZE" => Some(CmdResult::VpLayerUpdate {
+                vp_handle: self.vp_handle,
+                freeze: layer_names,
+                thaw: vec![],
+            }),
+            "T" | "THAW" => Some(CmdResult::VpLayerUpdate {
+                vp_handle: self.vp_handle,
+                freeze: vec![],
+                thaw: layer_names,
+            }),
+            _ => None, // unknown op — ignore
+        }
+    }
+
+    fn on_point(&mut self, _pt: Vec3) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        CmdResult::Cancel
+    }
+
+    fn on_mouse_move(&mut self, _pt: Vec3) -> Option<WireModel> {
+        None
+    }
+}