Clean up Graphic Attributes palette

- Revert formatting, import/module reordering and unrelated rewrites
  outside the feature (command.rs, style.rs, paper.rs, view/mod.rs,
  properties.rs, dialog.rs, ValuePromptCommand); the new SVG icons stay.
- Move the palette logic out of dialog.rs into update/graphic_attributes.rs.
- Replace 14 loose app fields and ~50 Message variants by
  GraphicAttributesState (one Menu enum for the open drop-down) and a
  nested GraphicAttributesMsg / GradientMsg, like BlockPaletteMsg.
- Share the selection -> line/fill handles -> unlocked edit path, reuse
  valid_block_name, the ribbon lineweight handler and fill_handles, and
  drop the unused GradientColorToggle, color_open and LineLinetypeScaleInput.
- Linetype scale accepts any positive value (e.g. ISO pen widths 0.13,
  0.18, 0.25, 0.35) instead of rounding to 0.1 with a 0.1 minimum.
- Closing open boundaries and creating the fill is one undo step.
- The close prompt also answers typed Y/N + Enter, a bare Enter (Yes)
  and Escape (cancel), not only the option buttons.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VgkJN8DEojuPTumAXLHotu

src/ui/dock.rs

@@ -273,7 +273,10 @@ mod tests {
     fn default_docks_each_known_panel_on_an_edge() {
         let state = DockState::default();
         assert_eq!(state.location(PanelId::Properties), Some((DockSide::Left, 0)));
-        assert_eq!(state.location(PanelId::GraphicAttributes), Some((DockSide::Left, 1)));
+        assert_eq!(
+            state.location(PanelId::GraphicAttributes),
+            Some((DockSide::Left, 1))
+        );
         assert_eq!(
             state.location(PanelId::BlockPalette),
             Some((DockSide::Right, 0))
@@ -373,4 +376,4 @@ mod tests {
         assert_eq!(drop_index(10.0, 2, 900.0), 0);
         assert_eq!(drop_index(890.0, 2, 900.0), 2);
     }
-}
+}