refactor(text): per-entity SDF text — all text kinds, selection/hover highlight

Rearchitect SDF text from a document-wide collector to per-entity
production during tessellation, so each entity owns its glyph quads and
composite/nested text is covered for free (no re-explosion, no per-frame
document walk).

- WireModel gains `text_verts`: glyph quads ride on the wire, so they are
  cached by the tess memo, cloned on hit, and transformed by the block
  expand loop exactly like `points`.
- Text arm (tessellate.rs) builds the quads when SDF is on and suppresses
  the strokes; render gathers text_verts from the viewport wire set
  (`gather_text_verts`, cached on wire content id) — the old collector is
  removed. Covers model, dimension, table, block-internal and paper-sheet
  text uniformly.
- MLEADER text (lays out via layout_mtext, not the Text arm) gets its own
  SDF branch driven by the per-run GlyphRun.
- Pick box comes from the rendered glyph quads (true text extent), not
  entity_aabb which mis-places the box for MTEXT; composite paths no longer
  clobber the empty text wire's tight AABB (dim pick box hugs the text).
- Selection / hover highlight via a text-highlight overlay (upload_text_
  highlight, keyed on selection_generation) mirroring the selected-wire
  xray overlay; base glyphs stay neutral so a deselect leaves no stale tint.
- Debug: env OCS_TEXT_BOX draws each run's glyph-bounds rectangle.

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

src/scene/pick/hit_test.rs

@@ -134,7 +134,48 @@ pub fn click_hit<'a>(
             }
         }
     }
-    best_fill.map(|(_, n)| n)
+    if let Some((_, n)) = best_fill {
+        return Some(n);
+    }
+
+    // SDF text renders as glyph quads, not strokes — its only pick target is
+    // the empty wire that carries the quads (`text_verts`) and the text's own
+    // tight AABB. Fall back to AABB containment so such text stays click-
+    // selectable, and use `text_verts` as the exact discriminator so only real
+    // text boxes qualify (never some other empty wire). Lowest priority — real
+    // edges and fills above always win. Prefer the tightest box so a click over
+    // overlapping text picks the smallest.
+    if crate::scene::text::sdf_atlas::sdf_text_enabled() {
+        let mut best_area = f32::MAX;
+        let mut best_box: Option<&str> = None;
+        for wire in wires {
+            if wire.text_verts.is_empty()
+                || !wire.points.is_empty()
+                || !wire.fill_tris.is_empty()
+                || wire.aabb == WireModel::UNBOUNDED_AABB
+            {
+                continue;
+            }
+            let [minx, miny, maxx, maxy] = wire.aabb;
+            let (mut sx0, mut sy0, mut sx1, mut sy1) = (f32::MAX, f32::MAX, f32::MIN, f32::MIN);
+            for (cx, cy) in [(minx, miny), (maxx, miny), (maxx, maxy), (minx, maxy)] {
+                let s = world_to_screen(glam::DVec3::new(cx as f64, cy as f64, 0.0), view_rot, eye, bounds);
+                sx0 = sx0.min(s.x);
+                sx1 = sx1.max(s.x);
+                sy0 = sy0.min(s.y);
+                sy1 = sy1.max(s.y);
+            }
+            if cursor.x >= sx0 && cursor.x <= sx1 && cursor.y >= sy0 && cursor.y <= sy1 {
+                let area = (sx1 - sx0) * (sy1 - sy0);
+                if area < best_area {
+                    best_area = area;
+                    best_box = Some(wire.name.as_str());
+                }
+            }
+        }
+        return best_box;
+    }
+    None
 }
 
 /// Like `click_hit` but returns every wire within the click threshold,

src/scene/pick/xclip.rs

@@ -610,6 +610,7 @@ mod tests {
 
         // A polyline half inside, half outside the 0..10 square.
         let mut wires = vec![WireModel {
+            text_verts: Vec::new(),
             points: vec![[5.0, 5.0, 0.0], [15.0, 5.0, 0.0]],
             ..Default::default()
         }];