feat(commands): prompt ATTDISP and LAYERSTATE by keyword

Add KeywordCommand, a generic stepped front-end for keyword sub-verb
commands: bare NAME shows the sub-verbs as clickable buttons, and picking
one either dispatches `NAME <verb>` (action verbs like ATTDISP On/Off/Normal)
or prompts for an argument and dispatches `NAME <verb> <value>` (LAYERSTATE
Save/Restore/Delete <name>). It delegates to the existing inline handler, so
the logic stays in one place. First two of bucket B converted; the rest
(VIEW, LINETYPE, SCALELISTEDIT, SETVAR, LAYDEL/LAYMRG, and the selection-first
XDATA/UNDERLAY/ADJUST/DRAWORDER/CHPROP) can follow the same pattern.

src/app/commands/draw.rs

@@ -149,7 +149,21 @@ impl OpenCADStudio {
             // ATTDISP ON   — make all AttributeDefinitions visible
             // ATTDISP OFF  — make all AttributeDefinitions invisible
             // ATTDISP NORMAL — restore: show only those without the invisible flag
-            cmd if cmd == "ATTDISP" || cmd.starts_with("ATTDISP ") => {
+            "ATTDISP" => {
+                use crate::command::KeywordCommand;
+                let c = KeywordCommand::new(
+                    "ATTDISP",
+                    "ATTDISP  attribute display  [On / Off / Normal]:",
+                    vec![
+                        ("On", "ON", None),
+                        ("Off", "OFF", None),
+                        ("Normal", "NORMAL", None),
+                    ],
+                );
+                self.command_line.push_info(&c.prompt());
+                self.tabs[i].active_cmd = Some(Box::new(c));
+            }
+            cmd if cmd.starts_with("ATTDISP ") => {
                 let sub = cmd.split_whitespace().nth(1).unwrap_or("").to_uppercase();
                 match sub.as_str() {
                     "ON" | "OFF" | "NORMAL" => {

src/app/commands/layers.rs

@@ -191,10 +191,22 @@ impl OpenCADStudio {
             // LAYERSTATE — save / restore named snapshots of all layer states
             // (on/off, freeze, lock, colour, linetype, lineweight).
             // LAYERSTATE SAVE <name> | RESTORE <name> | DELETE <name> | ? (list)
-            cmd if cmd == "LAYERSTATE"
-                || cmd == "LAS"
-                || cmd == "LMAN"
-                || cmd.starts_with("LAYERSTATE ")
+            "LAYERSTATE" | "LAS" | "LMAN" => {
+                use crate::command::KeywordCommand;
+                let c = KeywordCommand::new(
+                    "LAYERSTATE",
+                    "LAYERSTATE  [List / Save / Restore / Delete]:",
+                    vec![
+                        ("List", "LIST", None),
+                        ("Save", "SAVE", Some("LAYERSTATE SAVE  new state name:")),
+                        ("Restore", "RESTORE", Some("LAYERSTATE RESTORE  state name:")),
+                        ("Delete", "DELETE", Some("LAYERSTATE DELETE  state name:")),
+                    ],
+                );
+                self.command_line.push_info(&c.prompt());
+                self.tabs[i].active_cmd = Some(Box::new(c));
+            }
+            cmd if cmd.starts_with("LAYERSTATE ")
                 || cmd.starts_with("LAS ")
                 || cmd.starts_with("LMAN ") =>
             {