Put the rest of the selection settings on the Options card

Options → Selection already carried the pick box, the selection-area effect
and the grip visuals. Four settings behind it were finished, persisted and
reachable only by typing a system variable, and one more was a constant.

**Four that only needed a widget.** `SELECTIONEFFECT`, `SELECTIONPREVIEW`,
`PICKADD` and `PICKDRAG` are all wired end to end already. `SELECTIONEFFECT`
was the odd one: the card's own "Restore Defaults" button resets it, so it
could be turned off by a button and only turned back on from the command
line.

`SELECTIONPREVIEW` is a bitmask and gets one checkbox per bit, which is why
`set_preview_bit` exists rather than two inline expressions — the bits are
the thing this change is most able to get backwards.

The `PICKADD` checkbox is worded as AutoCAD words it, "use Shift to add to
selection", which is the *inverse* of the stored flag. That inversion is
commented at both ends; it reads as a bug otherwise.

**`GRIPOBJLIMIT`.** The limit past which a selection gets no grips arrived
with the selection work as a hardcoded 100, matching AutoCAD's default. It is
now a setting, a slider and a system variable, following `PICKBOX`'s path
exactly. AutoCAD's 0 means "no limit", which the old `>` comparison could not
express, so the read now guards on it — with a test, because zero is the one
value that would otherwise suppress every grip instead of allowing all of
them.

The slider covers 0..=1000, where every useful value lives; the sysvar takes
AutoCAD's full 0..=32767, and a larger value set from the command line parks
the handle at the end while the read-out keeps showing the real number.

**`SelectionPrefs`** replaces the `pick_box` parameter rather than adding
three more. `view_window` already took seventeen positional arguments, and
`pick_add` / `pick_drag_rect` are two adjacent `bool`s that would swap
silently at the call site.

**Two fixes found on the way.** `OPTIONS` and `OP` were registered for
autocomplete but never dispatched, so typing either answered "Unknown
command" and the dialog could only be opened from the start page. And the
`SELECTIONPREVIEW` doc comment had its bits the wrong way round — the code
reads `& 1` for the idle rollover and `& 2` for the in-command one, as
AutoCAD does — which would have put the two new checkboxes' labels backwards.

**Not done, deliberately.** `PICKFIRST` and `PICKAUTO` exist but are always
on, with no variable. `PICKSTYLE` is stored in the header and read by nobody
— group expansion decides from the group's own `selectable` flag — so an
"object grouping" checkbox would control nothing. Associative-hatch selection
does not exist as a selection behaviour. Each needs a behaviour change rather
than an exposure.

Of the ten new strings, en-US and el-GR are translated; the other nineteen
locales carry the English text. Composing them from existing keys, the way
el-GR composes the neighbouring labels, only works for one of the ten —
there is no existing key for "limit", "unlimited", "shift", "rectangle" or
"lasso", and "Grips: Objects" as the label of a numeric limit would be worse
than an untranslated string.

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

src/app/update/mod.rs

@@ -6103,6 +6103,50 @@ impl OpenCADStudio {
                 Task::none()
             }
 
+            Message::GripObjectLimitChanged(limit) => {
+                self.grip_object_limit = limit.clamp(0, 32767);
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
+            Message::SelectionEffectToggled(enabled) => {
+                self.model_space.selection_effect = enabled;
+                self.sync_model_space_theme(false);
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
+            // SELECTIONPREVIEW is a bitmask and the two checkboxes own one bit
+            // each: 1 = rollover while idle, 2 = rollover during a command.
+            Message::SelectionPreviewIdleToggled(enabled) => {
+                self.model_space.selection_preview =
+                    set_preview_bit(self.model_space.selection_preview, 1, enabled);
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
+            Message::SelectionPreviewCommandToggled(enabled) => {
+                self.model_space.selection_preview =
+                    set_preview_bit(self.model_space.selection_preview, 2, enabled);
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
+            // The checkbox is worded as AutoCAD words it — "use Shift to add"
+            // — which is the opposite of PICKADD, so it is inverted here rather
+            // than leaving a reader to work that out from the field name.
+            Message::ShiftToAddToggled(shift_to_add) => {
+                self.pick_add = !shift_to_add;
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
+            Message::PickDragRectToggled(rectangle) => {
+                self.pick_drag_rect = rectangle;
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
             Message::RestoreSelectionVisualDefaults => {
                 self.model_space.selection_area = true;
                 self.model_space.selection_opacity = 12;
@@ -6115,6 +6159,10 @@ impl OpenCADStudio {
                 self.model_space.grip_color = 0;
                 self.model_space.grip_hot = 0;
                 self.model_space.grip_hover = 0;
+                // The button restores the *visual* defaults, which is why the
+                // grip limit is here and PICKADD / PICKDRAG are not — those are
+                // how selection behaves, not how it looks.
+                self.grip_object_limit = crate::app::settings::DEFAULT_GRIP_OBJECT_LIMIT;
                 self.sync_model_space_theme(false);
                 self.persist_settings_if_changed();
                 Task::none()
@@ -8627,3 +8675,37 @@ mod free_text_entry_tests {
         assert_eq!(app.text_entry_mode(), TextEntryMode::Command);
     }
 }
+
+/// Set or clear one bit of `SELECTIONPREVIEW`.
+///
+/// The variable is a bitmask — 1 = rollover while no command is running,
+/// 2 = rollover during a command — and the Options card gives each bit its own
+/// checkbox. Worth a named function rather than two inline `|` / `& !`
+/// expressions: the config comment used to describe these bits the wrong way
+/// round, so the one place that names them is the place to be careful.
+fn set_preview_bit(current: u8, bit: u8, enabled: bool) -> u8 {
+    if enabled {
+        current | bit
+    } else {
+        current & !bit
+    }
+}
+
+#[cfg(test)]
+mod selection_preview_bit_tests {
+    use super::set_preview_bit;
+
+    #[test]
+    fn each_checkbox_owns_its_own_bit() {
+        // Both on, then clear the idle bit: the in-command bit must survive.
+        assert_eq!(set_preview_bit(3, 1, false), 2);
+        assert_eq!(set_preview_bit(3, 2, false), 1);
+        // Setting a bit that is already set changes nothing.
+        assert_eq!(set_preview_bit(3, 1, true), 3);
+        // From off, each bit turns on alone.
+        assert_eq!(set_preview_bit(0, 1, true), 1);
+        assert_eq!(set_preview_bit(0, 2, true), 2);
+        // Clearing both reaches 0, which is SELECTIONPREVIEW off.
+        assert_eq!(set_preview_bit(set_preview_bit(3, 1, false), 2, false), 0);
+    }
+}