feat(dyn): locked input fields constrain the preview and the click (#356)

A typed dynamic-input value (TAB-locked angle or distance) now shapes
the rubber-band: the cursor point is routed through dyn_resolve_point —
the same resolution Enter commits — in the mouse-move preview and the
click commit, so a locked 30° pins the line's direction while the free
field keeps tracking the cursor. The lock wins over osnap/ortho/polar.
TAB (and the comma advance) reshape the preview immediately instead of
waiting for the next mouse move.

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

src/app/update/command.rs

@@ -83,6 +83,7 @@ pub(super) fn on_tab_close(&mut self, idx: usize) -> Task<Message> {
                     if s == "," && self.dyn_input && !self.tabs[i].dyn_fields.is_empty() {
                         self.dyn_comma_advance();
                         self.command_line.autocomplete_cursor = None;
+                        self.refresh_active_cmd_preview(i);
                         return self.focus_cmd_input();
                     }
                     // While dynamic input is showing fields, numeric and