fix(export): render SDF text as vectors in PDF/print export (#385)

Since text became SDF-only (the legacy stroke-text path was removed), all
text — standalone TEXT/MTEXT and dimension text — rendered on-screen only as
GPU glyph quads carried on `WireModel::text_verts`. The CPU PDF/print exporter
draws only wire stroke `points` and hatch fills, so it silently dropped every
glyph: dimensions and text were missing from exported PDFs and prints
(present in v0.7.6).

Reconstruct vector text in the exporter instead of resurrecting the stroke
path, so the SDF render path and its caching are untouched:

- sdf_atlas: `GlyphAtlas::export_table()` snapshots each baked glyph's vector
  geometry (outline strokes + fill triangles, glyph space) keyed by its tile
  `uv_min`, re-resolved through `Face` so it honours the current TEXTFILL.
- pdf_export: a new `emit_text` pass walks each wire's `text_verts` (one
  6-vertex quad per glyph), recovers the glyph geometry by `uv_min`, and
  affine-maps it into the quad — `DrawLine` polylines for stroke (LFF/SHX)
  fonts, filled triangles for TrueType, plus solid decoration bars. Runs under
  the same rotation/scale/clip CTM as the wires, so it covers model space,
  paper space and windowed plots, and every SDF-text kind (text, dimension,
  multileader, table, tolerance).

Text embedded in complex linetypes is SDF-only with no stroke fallback and
stays out of scope.

Tests: a unit test asserts a stroke glyph emits vector ops within the glyph's
world bbox; an integration test drives a real TEXT + linear DIMENSION through
scene.entity_wires() -> export_pdf and checks text reaches the file. Verified
bug-first: with emit_text disabled the end-to-end test fails with the reported
symptom (text adds no content).

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

tests/pdf_export_text_check.rs

@@ -0,0 +1,69 @@
+// Regression for #385: text and dimension text must reach the PDF / print
+// export. From v0.8.2 text renders on-screen only as GPU SDF glyph quads
+// (`WireModel::text_verts`); the CPU PDF exporter used to draw only wire
+// stroke `points`, so all text — standalone TEXT/MTEXT and dimension text —
+// vanished from exported PDFs (present in v0.7.6). This drives the real
+// entity -> scene.entity_wires() -> export_pdf path and asserts text is
+// carried to the exporter and lands in the file.
+use acadrust::entities::{Dimension, DimensionLinear, Text};
+use acadrust::types::Vector3;
+use acadrust::EntityType;
+use OpenCADStudio::io::pdf_export::export_pdf;
+use OpenCADStudio::scene::Scene;
+
+#[test]
+fn text_and_dim_reach_pdf_export() {
+    let mut scene = Scene::new();
+
+    // A standalone TEXT entity.
+    let t = Text::with_value("HELLO", Vector3::new(10.0, 10.0, 0.0)).with_height(5.0);
+    scene.add_entity(EntityType::Text(t));
+
+    // A linear dimension — its measurement value is synthesized as SDF text
+    // too, so it exercises the dimension-text path the reporters called out.
+    let dim = DimensionLinear::new(
+        Vector3::new(0.0, 0.0, 0.0),
+        Vector3::new(40.0, 0.0, 0.0),
+    );
+    scene.add_entity(EntityType::Dimension(Dimension::Linear(dim)));
+
+    let wires = scene.entity_wires();
+
+    // The regression symptom was that text produced no exportable geometry.
+    // It must now ride the export wire set as SDF glyph quads.
+    let text_wires = wires.iter().filter(|w| !w.text_verts.is_empty()).count();
+    assert!(
+        text_wires > 0,
+        "no text_verts on the export wire set — text/dim text would be missing from the PDF"
+    );
+
+    // End-to-end: exporting with the text present must produce a valid PDF that
+    // is larger than the same wire set with the text stripped — i.e. the glyph
+    // geometry actually reaches the file.
+    let dir = std::env::temp_dir();
+    let p_text = dir.join("ocs_385_with_text.pdf");
+    export_pdf(&wires, &[], &[], 210.0, 297.0, 0.0, 0.0, 0, 1.0, None, &p_text, None)
+        .expect("export with text");
+    let with_text = std::fs::read(&p_text).expect("read pdf");
+    assert!(with_text.starts_with(b"%PDF"), "not a PDF");
+
+    let stripped: Vec<_> = wires
+        .iter()
+        .cloned()
+        .map(|mut w| {
+            w.text_verts.clear();
+            w
+        })
+        .collect();
+    let p_bare = dir.join("ocs_385_no_text.pdf");
+    export_pdf(&stripped, &[], &[], 210.0, 297.0, 0.0, 0.0, 0, 1.0, None, &p_bare, None)
+        .expect("export without text");
+    let no_text = std::fs::read(&p_bare).expect("read pdf");
+
+    assert!(
+        with_text.len() > no_text.len(),
+        "text added no content to the PDF: {} !> {}",
+        with_text.len(),
+        no_text.len()
+    );
+}