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 <[email protected]>

src/app/mod.rs

@@ -500,6 +500,9 @@ pub(super) struct OpenCADStudio {
     cursor_size: i32,
     /// Selection-box size setting (PICKBOX, 0..=50).
     pick_box: i32,
+    /// Selected-object count past which grips stop being generated
+    /// (GRIPOBJLIMIT, 0..=32767; 0 = no limit).
+    grip_object_limit: i32,
     /// Drawing viewport cursor style (CURSORTYPE).
     cursor_type: settings::CursorType,
     /// Explicit crosshair colour; `None` retains automatic contrast.
@@ -1977,6 +1980,20 @@ pub enum Message {
     GripHotChanged(u8),
     /// Change Hover/Warm Grip color ACI index (0 = Theme Primary Strong, 1..=255 = ACI, GRIPHOVER).
     GripHoverChanged(u8),
+    /// Change the selected-object count past which grips stop being drawn
+    /// (0..=32767, 0 = no limit, GRIPOBJLIMIT).
+    GripObjectLimitChanged(i32),
+    /// Toggle the solid selection highlight (SELECTIONEFFECT).
+    SelectionEffectToggled(bool),
+    /// Toggle rollover preview while no command is running (SELECTIONPREVIEW bit 1).
+    SelectionPreviewIdleToggled(bool),
+    /// Toggle rollover preview during a command (SELECTIONPREVIEW bit 2).
+    SelectionPreviewCommandToggled(bool),
+    /// Toggle "use Shift to add to selection" — the checkbox reads the way
+    /// AutoCAD words it, so it carries the *inverse* of PICKADD.
+    ShiftToAddToggled(bool),
+    /// Toggle press-and-drag drawing a rectangle instead of a lasso (PICKDRAG).
+    PickDragRectToggled(bool),
     /// Restore Model Space display/canvas appearance to defaults.
     RestoreModelSpaceDisplayDefaults,
     /// Restore Selection visual effect settings to defaults.
@@ -3369,6 +3386,7 @@ impl OpenCADStudio {
             zoom_factor: 60,
             cursor_size: 5,
             pick_box: 3,
+            grip_object_limit: settings::DEFAULT_GRIP_OBJECT_LIMIT,
             cursor_type: settings::CursorType::Crosshair,
             crosshair_color: None,
             crosshair_color_input: String::new(),