Feat: implement CTB/STB plot style table with PDF export integration

- src/io/plot_style.rs: PlotStyleTable and PlotStyleEntry data structures;
  CTB reader (deflate/zlib decompressed text format) with ACI→RGB and
  ACI→lineweight lookup; CTB writer (zlib compressed); LW_TABLE constant
- src/io/pdf_export.rs: accept optional PlotStyleTable; apply ACI color
  and lineweight overrides during PDF rendering
- src/scene/wire_model.rs: add `aci: u8` field to carry ACI index
- src/scene/render.rs: render_style() now returns ACI alongside RGBA
- src/scene/mod.rs + tessellate.rs: propagate aci through wire building
- app: PlotStyleLoad/Loaded/Clear messages and handlers;
  PLOTSTYLE LOAD | CLEAR | STATUS command; active_plot_style state on H7CAD
- flate2 added as dependency

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/io/pdf_export.rs

@@ -9,6 +9,7 @@
 // drawing origin at the paper origin.
 
 use crate::scene::WireModel;
+use crate::io::plot_style::PlotStyleTable;
 use printpdf::{Color, Line, LineCapStyle, LineJoinStyle, LinePoint, Mm, Op, PdfDocument,
                PdfPage, PdfSaveOptions, Point, Pt, Rgb};
 use std::io::Write;
@@ -30,8 +31,9 @@ pub fn export_pdf(
     offset_y: f32,
     rotation_deg: i32,
     path: &Path,
+    plot_style: Option<&PlotStyleTable>,
 ) -> Result<(), String> {
-    let bytes = build_pdf(wires, paper_w as f32, paper_h as f32, offset_x, offset_y, rotation_deg);
+    let bytes = build_pdf(wires, paper_w as f32, paper_h as f32, offset_x, offset_y, rotation_deg, plot_style);
     let mut file = std::fs::File::create(path).map_err(|e| e.to_string())?;
     file.write_all(&bytes).map_err(|e| e.to_string())
 }
@@ -50,7 +52,7 @@ pub async fn pick_pdf_path_owned(stem: String) -> Option<std::path::PathBuf> {
 
 // ── PDF builder ───────────────────────────────────────────────────────────
 
-fn build_pdf(wires: &[WireModel], paper_w: f32, paper_h: f32, ox: f32, oy: f32, rotation_deg: i32) -> Vec<u8> {
+fn build_pdf(wires: &[WireModel], paper_w: f32, paper_h: f32, ox: f32, oy: f32, rotation_deg: i32, plot_style: Option<&PlotStyleTable>) -> Vec<u8> {
     let mut doc = PdfDocument::new("H7CAD Export");
     let mut ops: Vec<Op> = Vec::new();
 
@@ -93,6 +95,10 @@ fn build_pdf(wires: &[WireModel], paper_w: f32, paper_h: f32, ox: f32, oy: f32,
 
     let mut last_color: Option<[f32; 3]> = None;
     let mut last_lw: Option<f32> = None;
+    // mm to PDF points (1 mm = 2.834645 pt).
+    const MM_TO_PT: f32 = 2.834645;
+    // Screen px to PDF points (approximate at 96 dpi).
+    const PX_TO_PT: f32 = 0.35278;
 
     for wire in wires {
         let [mut r, mut g, mut b, a] = wire.color;
@@ -103,15 +109,29 @@ fn build_pdf(wires: &[WireModel], paper_w: f32, paper_h: f32, ox: f32, oy: f32,
         if wire.name == "__paper_boundary__" {
             continue;
         }
-        // Near-white and near-yellow (viewport active border) → dark grey for print.
-        let is_light = r > 0.80 && g > 0.80 && b > 0.80;
-        let is_yellow = r > 0.80 && g > 0.70 && b < 0.30;
-        let is_cyan   = r < 0.30 && g > 0.70 && b > 0.70;
-        if is_light || is_yellow {
-            r = 0.0; g = 0.0; b = 0.0;
-        } else if is_cyan {
-            // Viewport border: print as dark blue.
-            r = 0.0; g = 0.15; b = 0.50;
+        // Apply CTB plot style table overrides (color + lineweight).
+        let mut lw_override: Option<f32> = None;
+        if let Some(ctb) = plot_style {
+            if wire.aci > 0 {
+                if let Some([cr, cg, cb]) = ctb.resolve_color(wire.aci) {
+                    r = cr; g = cg; b = cb;
+                }
+                lw_override = ctb.resolve_lineweight(wire.aci)
+                    .map(|mm| (mm * MM_TO_PT).max(0.1));
+            }
+        }
+        // Near-white and near-yellow (viewport active border) → dark grey for print
+        // (only when no CTB override was applied).
+        if lw_override.is_none() {
+            let is_light = r > 0.80 && g > 0.80 && b > 0.80;
+            let is_yellow = r > 0.80 && g > 0.70 && b < 0.30;
+            let is_cyan   = r < 0.30 && g > 0.70 && b > 0.70;
+            if is_light || is_yellow {
+                r = 0.0; g = 0.0; b = 0.0;
+            } else if is_cyan {
+                // Viewport border: print as dark blue.
+                r = 0.0; g = 0.15; b = 0.50;
+            }
         }
 
         if last_color.map(|c| {
@@ -123,8 +143,9 @@ fn build_pdf(wires: &[WireModel], paper_w: f32, paper_h: f32, ox: f32, oy: f32,
             last_color = Some([r, g, b]);
         }
 
-        // Line weight: screen px → points (approximate 1 px ≈ 0.35 pt).
-        let lw_pt = (wire.line_weight_px * 0.35278_f32).max(0.1);
+        // Line weight: CTB override (in pt) or screen px → points.
+        let lw_pt = lw_override
+            .unwrap_or_else(|| (wire.line_weight_px * PX_TO_PT).max(0.1));
         if last_lw.map(|l| (l - lw_pt).abs() > 0.01).unwrap_or(true) {
             ops.push(Op::SetOutlineThickness { pt: Pt(lw_pt) });
             last_lw = Some(lw_pt);