fix(dyn-input): re-sync fields immediately after point commits (#35)

`sync_dyn_fields` only ran during `ViewportMove`, so a typed-coord
or click-driven point commit left the previous iteration's field
shape in place until the user nudged the mouse. After the first
LINE click that meant the stale `[X, Y]` (built when there was no
base) kept serving the next point's input as cartesian even though
the command-default for a "Point with base" is now polar
`[Distance, Angle]`. The original #35 fix preserved a
`,`-reshaped cartesian set on purpose, but the same machinery now
also held onto a never-explicitly-chosen `[X, Y]` carried over from
"no base" → "has base".

Track that intent explicitly with `dyn_user_reshaped` (set in
`dyn_comma_advance`, cleared on point commit and command start)
and only treat a non-matching shape as acceptable while that flag
is on. Re-run `sync_dyn_fields` from every point-commit path
(command-line typed coord, mouse click, dynamic-input locked
commit) so the freshly updated `has_base` state immediately picks
the right default and the user sees polar fields without having
to move the mouse first.

src/app/mod.rs

@@ -88,6 +88,12 @@ pub(super) struct OpenCADStudio {
     /// edge, updated on move, cleared on release (which also runs the
     /// collapse pass).
     tile_drag: Option<TileDrag>,
+    /// `true` once the user has reshaped the dynamic-input field set via
+    /// the `,` separator during the current command iteration. Tells
+    /// `sync_dyn_fields` to preserve the user's chosen shape instead of
+    /// reverting to the command-default when `has_base` flips. Cleared
+    /// on point commit / command start. See #35.
+    dyn_user_reshaped: bool,
     /// Show the UCS icon in the bottom-left corner of model space (UCSICON).
     show_ucs_icon: bool,
     /// Whether the ViewCube 3D gizmo is visible in model space (NAVVCUBE).
@@ -763,6 +769,7 @@ impl OpenCADStudio {
             dyn_input: true,
             awaiting_vports: false,
             tile_drag: None,
+            dyn_user_reshaped: false,
             show_ucs_icon: true,
             show_viewcube: true,
             show_properties: true,