fix: suppress console window in release builds

[Copilot]

• Add #![cfg_attr(all(not(debug_assertions), target_os = "windows"), windows_subsystem = "windows")] to src/main.rs to disable the console window in release builds, scoped to Windows targets only

Original prompt

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This section details on the original issue you should resolve

<issue_title>Release is compiled in console mode instead of window mode</issue_title>
<issue_description>### Release is compiled in console mode instead of window mode

Description
As pointed out by @jyonxo, The current release build is compiled in console mode rather than window (GUI) mode. As a result, launching the application opens an accompanying console window, which is not expected behaviour for a release build.

Expected behaviour

• Release builds should be compiled in window/GUI mode
• No console window should appear when launching the application

Actual behavior

• Application launches with a visible console window
• Indicates the binary was compiled with console subsystem enabled

Impact

• Unintended console window shown to end users
• Reduces polish and may confuse users in production

Notes

• Likely related to build configuration (e.g. subsystem setting, linker flags, or entry point)
• Debug builds may be unaffected / acceptable, but release builds should not use console mode
  ``
  </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Release is compiled in console mode instead of window mode #17

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[Copilot]

Pull request overview

This PR updates the Rust crate entrypoint to build as a Windows GUI application in release mode, preventing an unwanted console window from appearing when end users launch the app on Windows.

Changes:

• Add a crate-level cfg_attr to set windows_subsystem = "windows" for Windows non-debug builds.

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