Generate .ico from SVG on Windows release builds.

windows/build.rs

@@ -0,0 +1,51 @@
+use std::process::Command;
+
+fn main() {
+    #[cfg(target_os = "windows")]
+    {
+        let svg = "../assets/Acord.svg";
+        let ico = "icon.ico";
+        let tmp = "icon_tmp";
+
+        // Only regenerate on release builds or when the SVG changes.
+        println!("cargo:rerun-if-changed={svg}");
+
+        let _ = std::fs::create_dir_all(tmp);
+        let sizes = [16, 24, 32, 48, 64, 128, 256];
+        let mut pngs = Vec::new();
+
+        for size in sizes {
+            let out = format!("{tmp}/icon_{size}.png");
+            let s = size.to_string();
+            let ok = Command::new("rsvg-convert")
+                .args(["--width", &s, "--height", &s, svg, "-o", &out])
+                .status()
+                .map(|s| s.success())
+                .unwrap_or(false);
+            if !ok {
+                eprintln!("cargo:warning=rsvg-convert failed for {size}px — skipping icon embed");
+                let _ = std::fs::remove_dir_all(tmp);
+                return;
+            }
+            pngs.push(out);
+        }
+
+        let ok = Command::new("magick")
+            .args(pngs.iter().map(|s| s.as_str()))
+            .arg(ico)
+            .status()
+            .map(|s| s.success())
+            .unwrap_or(false);
+
+        let _ = std::fs::remove_dir_all(tmp);
+
+        if !ok {
+            eprintln!("cargo:warning=magick ico conversion failed — skipping icon embed");
+            return;
+        }
+
+        let mut res = winres::WindowsResource::new();
+        res.set_icon(ico);
+        res.compile().expect("winres icon embed");
+    }
+}