fix(windows): embed the app icon into the .exe

The Windows executable carried no icon, so Explorer, the taskbar, the
Start-menu tile and file-association entries showed a generic icon. Embed
AppIcon.ico via winresource in build.rs, and generate the .ico from the logo
before the build (it was produced after the build, too late to embed). Local
and non-Windows builds skip the step when the .ico is absent.

Fixes #107.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

build.rs

@@ -26,6 +26,22 @@ use std::path::Path;
 const PRIORITY: &[&str] = &["home", "model", "insert", "annotate", "view", "manage"];
 
 fn main() {
+    // Windows: embed AppIcon.ico into the .exe so the executable carries its
+    // own icon (Explorer, taskbar, Start-menu tile, file associations). The
+    // .ico is produced from assets/logo.svg by the release workflow before the
+    // build; when it is absent (local/dev builds) this is skipped. See #107.
+    #[cfg(windows)]
+    {
+        println!("cargo:rerun-if-changed=packaging/windows/AppIcon.ico");
+        if Path::new("packaging/windows/AppIcon.ico").exists() {
+            let mut res = winresource::WindowsResource::new();
+            res.set_icon("packaging/windows/AppIcon.ico");
+            if let Err(e) = res.compile() {
+                println!("cargo:warning=failed to embed Windows icon: {e}");
+            }
+        }
+    }
+
     let mods_dir = Path::new("src/modules");
     println!("cargo:rerun-if-changed=src/modules");