fix(zoom): Zoom Extents fits full drawing on first use

The viewport context-menu item dispatched a bare "ZOOM" string, which no
command branch handled, so it did nothing. Send "ZOOM EXTENTS" instead.

fit_all() also fed on the frustum-culled wire set, so it only framed the
entities already on screen — each invocation revealed a little more and the
view converged on the true extent only after several uses (issue #51). It
now builds an un-culled wire set at a fixed tessellation tolerance, so the
bounds are zoom-independent and the first call fits the whole drawing.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/scene/mod.rs

@@ -4948,7 +4948,17 @@ impl Scene {
     }
 
     pub fn fit_all(&mut self) {
-        let wires = self.entity_wires();
+        // Use the FULL, un-culled wire set — not `entity_wires()`, which is
+        // frustum-culled to the current view. Culled input would fit only the
+        // entities already on screen, so each call would zoom out a little and
+        // reveal more, converging on the true extent only after several uses
+        // (issue #51). `wpp = None` also tessellates at a fixed tolerance so
+        // the bounds don't drift with zoom-adaptive curve sampling.
+        let layout_block = self.current_layout_block_handle();
+        let mut wires = self.wires_for_block_culled(layout_block, None, None, None, None);
+        if self.current_layout != "Model" {
+            wires.extend(self.viewport_content_wires(layout_block, None, None));
+        }
         if wires.is_empty() {
             return;
         }