Merge pull request #1423 from felixriestra:pr/python-host-model

The bundled `opencad.python` plugin drives OCS through plugin API v7: all
43 canvas entity kinds, the drawing tables, and OCS's own commands run
step by step. RustPython stays in the plugin process — the plugin crate is
outside the workspace with its own lock file, so the application's own
dependencies are unchanged.

Reconciled with the plugin command work that landed as #1425, which the
branch was written before:

- Both added `impl Drop for PluginProcessInteractiveAdapter`, which git
  merges silently into two impls that do not compile. One body now
  cancels the command and then drops it from the runner, in that order: a
  plugin waiting on a step has to be released before the runner forgets
  the command.
- `execute_command` (#1425) and `run_command` (#1423) are both routes from
  a script to the command line, and only the second was guarded. The
  SCRIPTCOMMANDS switch and the denylist are shared now, so neither route
  is the unguarded one.
- `run_command` dispatched with plugin dispatch still enabled, so a script
  naming a plugin command re-entered the plugin that was blocked waiting
  for it. It sets the suppression flag for the length of the dispatch, as
  `execute_command` does.

The denylist read the command as typed, while the dispatcher resolves
aliases: a user-defined `Q` for `QUIT` (ALIASEDIT writes those) walked
past it. It resolves the alias first.

Also: the active-command comparison ran on every message, a mouse move
included, allocating two strings for names that are already `&'static
str`; SCRIPTCOMMANDS' own messages go through the translation macros; and
`docs/.DS_Store` (now ignored) and an unrelated RTF note about constraint
commands are out of the tree.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/app/settings.rs

@@ -485,6 +485,10 @@ pub struct UserSettings {
     /// Minutes between autosaves to a `.sv$` recovery file (SAVETIME command).
     /// 0 disables autosave.
     pub savetime_min: i32,
+    /// SCRIPTCOMMANDS: whether a script (the Python plugin) may run OCS commands
+    /// through the host. On by default; a user turns it off with the
+    /// `SCRIPTCOMMANDS 0` command, and a script cannot change it.
+    pub script_commands: bool,
     /// File type and version used when a new/unsaved drawing is first saved.
     /// Existing drawings keep their own type and version.
     pub default_save_format: String,
@@ -685,6 +689,7 @@ impl Default for UserSettings {
             constraint_bar_display: 3,
             constraint_bar_mode: 4095,
             savetime_min: 10,
+            script_commands: true,
             default_save_format: crate::io::DEFAULT_SAVE_FORMAT.to_string(),
             pick_add: true,
             pick_drag_rect: false,
@@ -798,6 +803,19 @@ mod tests {
         assert_eq!(cfg.settings.savetime_min, 42);
     }
 
+    #[test]
+    fn script_commands_default_on_and_survive_a_round_trip() {
+        let missing: crate::app::config::AppConfig =
+            serde_json::from_str(r#"{"settings": {"pick_add": false}}"#).unwrap();
+        assert!(missing.settings.script_commands, "an old config keeps scripts allowed");
+        let off: crate::app::config::AppConfig =
+            serde_json::from_str(r#"{"settings": {"script_commands": false}}"#).unwrap();
+        assert!(!off.settings.script_commands);
+        let text = serde_json::to_string(&off).unwrap();
+        let back: crate::app::config::AppConfig = serde_json::from_str(&text).unwrap();
+        assert!(!back.settings.script_commands);
+    }
+
     #[test]
     fn isometric_drafting_never_persists_or_loads() {
         // A persisted On used to bring the isoplane crosshair (vertical +