Harden Windows resource embedding and add exe metadata and manifest

[cyb0rg56]

Summary

The build script now checks the platform it's building for, reruns only when its own inputs change, and uses a maintained resource crate. The .exe also gains version details and an application manifest with per-monitor DPI awareness.

Changes

• build.rs

  • Checks CARGO_CFG_TARGET_OS instead of #[cfg(windows)], so it looks at the platform being built for rather than the build machine. Cross-compiling to Windows now embeds resources correctly.
  • Adds rerun-if-changed for build.rs, icon.ico and app.manifest. Before this, edits to any file in the root package (including docs and packaging) reran the script.
  • Sets the icon with set_icon_with_id("icon.ico", "1"). tray.rs loads the tray icon from resource ID 1, and that link was previously only implied by a default.
  • Embeds ProductName, FileDescription and LegalCopyright. The file and product versions come from the Cargo package version.
  • Embeds app.manifest.
  • main returns std::io::Result<()> instead of calling .unwrap().

• Cargo.toml

  • Replaces winres 0.1 (unmaintained) with winresource 0.1 (maintained fork, same API).
  • Removes the redundant [[bin]] section. main.rs and the binary name are Cargo's defaults.

• app.manifest (new)

  • PerMonitorV2 DPI awareness, with true/pm as a fallback for older Windows.
  • UTF-8 active code page.
  • Declares Windows 10/11 as a supported OS.
  • asInvoker execution level, so the app never asks for admin rights.