Type Object Selection by Path Only: every baseline, Type tool and Eyedropper (review of #475)

- Type is picked on the baseline of any of its lines (point type and area
  type, besides area type's frame), as in Illustrator, not only the first
  one: the layout's baselines are cached with its bounds
  (`TextObject::cached_baselines`, from `TextLayout::baselines`), with the
  first one across the bounds as the fallback. Vertical type's runs down
  each column's centre line.
- Type in perspective is picked where it is drawn (through its projection).
- The bounds rule type out before its path is built, so hovering stays
  free of allocations away from type.
- The Type tools still edit type clicked among its characters (they made
  new type there with the preference on), and the Eyedropper still samples
  it there, as it does inside fills with Object Selection by Path Only.
- Tests for all of it; docs/mcp.md and ROADMAP say so.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/clipboard/flavours.rs

@@ -300,7 +300,7 @@ fn import_text(s: &mut Session, p: &Value) -> Result<Value> {
         return Err(bad(C, "the text is empty"));
     }
     let mut t = TextObject::point(Point::ZERO, text, super::super::create::new_type_style(s, &Value::Null));
-    t.cached_bounds = Some(vectorcraft_text::layout(vectorcraft_text::FontDb::global(), &t).bounds);
+    crate::cmd::typecmd::refresh_bounds(&mut t);
     let n = Node::new(NodeId(1), NodeKind::Text(Box::new(t)));
     let count = s.load_clipboard(Clipboard { nodes: vec![n], ..Default::default() }, p)?;
     Ok(json!({ "count": count }))

crates/engine/src/cmd/place/text.rs

@@ -197,8 +197,7 @@ pub(super) fn area_text(text: String, frame: Rect) -> vectorcraft_doc::TextObjec
         run.text = text;
     }
     t.kind = vectorcraft_doc::TextKind::Area { frame: shapes::rectangle(Rect::from_origin_size(Point::ORIGIN, frame.size())) };
-    let lay = vectorcraft_text::layout(vectorcraft_text::FontDb::global(), &t);
-    t.cached_bounds = Some(lay.bounds);
+    crate::cmd::typecmd::refresh_bounds(&mut t);
     t
 }
 

crates/engine/src/cmd/textedit.rs

@@ -469,6 +469,7 @@ fn create_in_path(s: &mut Session, p: &Value) -> Result<Value> {
         path_spacing: 0.0,
         wrap: Vec::new(),
         cached_bounds: None,
+        cached_baselines: Vec::new(),
     };
     if bool_or(p, "placeholder", false) {
         super::typemenu::fill_with_placeholder(&mut t);
@@ -601,6 +602,7 @@ fn headline_tracking(t: &TextObject, target: f64) -> Option<f64> {
             path_spacing: 0.0,
             wrap: Vec::new(),
             cached_bounds: None,
+            cached_baselines: Vec::new(),
         };
         for r in &mut h.runs {
             r.style.tracking = tr;

crates/engine/src/cmd/typecmd.rs

@@ -97,10 +97,11 @@ fn orientation(s: &mut Session, p: &Value, vertical: bool) -> Result<Value> {
     Ok(json!({"vertical": vertical, "ids": ids.iter().map(|id| id.0).collect::<Vec<_>>()}))
 }
 
-/// Recompute the layout bounds cache after a text edit.
+/// Recompute the layout caches (bounds and baselines) after a text edit.
 pub(crate) fn refresh_bounds(t: &mut TextObject) {
     let lay = vectorcraft_text::layout(vectorcraft_text::FontDb::global(), t);
     t.cached_bounds = Some(lay.bounds);
+    t.cached_baselines = lay.baselines();
 }
 
 /// Text objects among `ids` and their descendants.