feat(commands): step the selection-first text commands (bucket C)

Add SelectThenValueCommand (gather selection, then one value) and convert:
- SelectThenValueCommand: HYPERLINK (url), ARCTEXT (text), TEXTFIT (width),
  SCALETEXT (factor), TCOUNT (start), TEXTMASK (Enter to apply).
- SelectThenKeywordCommand: JUSTIFYTEXT (Left/Center/Right/Middle/Aligned/Fit),
  TCASE (Upper/Lower/Sentence/Title).

Each bare form gathers a selection when none is set, prompts, and delegates to
the inline handler. OBJECTSCALE already opens its dialog; TABLE CELL takes three
values (row/col/text) and stays typeable — TABLE bare already builds a table
interactively.

src/app/commands/styleprops.rs

@@ -1848,7 +1848,18 @@ impl OpenCADStudio {
             // ── SCALETEXT — rescale selected Text/MText entities ─────────────────
             // Usage: SCALETEXT <factor>   e.g. SCALETEXT 2
             //        SCALETEXT H <height>  set absolute height
-            cmd if cmd == "SCALETEXT" || cmd.starts_with("SCALETEXT ") => {
+            "SCALETEXT" => {
+                use crate::command::SelectThenValueCommand;
+                let has_sel = !self.tabs[i].scene.selected_entities().is_empty();
+                let c = SelectThenValueCommand::new(
+                    "SCALETEXT",
+                    "SCALETEXT  scale factor (or 'H <height>' for an absolute height):",
+                    has_sel,
+                );
+                self.command_line.push_info(&c.prompt());
+                self.tabs[i].active_cmd = Some(Box::new(c));
+            }
+            cmd if cmd.starts_with("SCALETEXT ") => {
                 let rest = cmd.trim_start_matches("SCALETEXT").trim();
                 let parts: Vec<&str> = rest.split_whitespace().collect();
                 let selected_handles: Vec<acadrust::Handle> = self.tabs[i]