feat(text): parse TEXT via acadrust + extend SDF text to MTEXT

Two related steps for the text pipeline:

- TEXT parsing now goes through acadrust's parse_plain_text (like MTEXT
  uses parse_mtext). text::acad_text_encode parses the value's %% codes —
  including %%u/%%o underline/overline and %%nnn — and re-encodes to the
  stroke tessellator's \L/\O + resolved-Unicode grammar, so OCS no longer
  tokenizes TEXT %% codes itself. (ATTRIB/TOLERANCE/DIMENSION still use the
  local tokenizer for now.) Bumps the acadrust pin to the commit that
  completes the TEXT/MTEXT control-code set.

- SDF text (OCS_TEXT_SDF) now covers MTEXT and every text-producing
  entity, not just top-level TEXT. TextStroke carries a GlyphRun (layout
  params); the collector walks convert()'s TruckObject::Text runs and
  applies annotation scale exactly as tessellate does for strokes.
  layout_glyph_quads shares lff::tokenize_run so %% specials resolve and
  \L/\O decorations are skipped (decoration LINES in SDF are still TODO).

Verified: stroke rendering unchanged with the flag off; SDF glyphs render
correctly for TEXT and MTEXT with OCS_TEXT_SDF=1. 154 lib tests green.

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

src/entities/text_support.rs

@@ -1,7 +1,7 @@
 use acadrust::types::aci_table::aci_to_rgb;
 use acadrust::{CadDocument, EntityType};
 
-use crate::scene::convert::acad_to_truck::TextStroke;
+use crate::scene::convert::acad_to_truck::{GlyphRun, TextStroke};
 use crate::scene::text::font_face::Face;
 use crate::scene::text::lff;
 
@@ -1175,6 +1175,17 @@ pub fn layout_mtext(opts: &MTextRenderOpts) -> MTextLayout {
                         origin,
                         color,
                         fill_tris,
+                        // `text` is the plain word (specials already resolved,
+                        // no decoration markers); `run_h` is raw like the strokes.
+                        run: Some(GlyphRun {
+                            text: text.clone(),
+                            font: font_name.to_string(),
+                            height: run_h,
+                            rotation: rot,
+                            width_factor: signed_wf,
+                            oblique,
+                            tracking,
+                        }),
                     });
                     if opts.want_glyph_boxes {
                         // Per-character boxes, advancing exactly as