Add macOS and Windows screensaver build for weathr

[Matroskin86]

Description:
Currently, weathr is a terminal-based CLI application. Users cannot install it as a native screensaver on macOS or Windows. This feature request proposes packaging weathr as a screensaver that runs the ASCII weather animation in the screensaver context.

Problem:

• macOS requires .saver bundles implementing a ScreenSaverView class.
• Windows requires .scr files handling standard screensaver callbacks.
• Currently, users must run weathr manually in the terminal; no native screensaver option exists.

Proposed Solution:

1. Implement a wrapper module for macOS:
   • Create a .saver bundle
   • Implement ScreenSaverView subclass that launches weathr internally
   • Render ASCII animation inside the screensaver window
2. Implement a wrapper module for Windows:
   • Compile a .scr file
   • Handle standard screensaver messages (WM_PAINT, WM_CLOSE, WM_SYSCOMMAND)
   • Launch weathr animation inside a dedicated window
3. Add build targets in Cargo for each platform
4. Optional: allow config options for location, units, and animation style

Alternatives:

• Run weathr inside a fullscreen terminal emulator, but this is not a proper native screensaver.

Additional Context:

• macOS .saver bundles must declare NSPrincipalClass = ScreenSaverView in Info.plist
• Windows .scr are essentially .exe with screensaver callbacks

Goal:
Enable users to run weathr as a true native screensaver on both macOS and Windows, preserving the ASCII weather animation.

[marcohoovy]

I did personally try and add this for Windows but it never got to the PR stage because it wasn't a very clean solution. I would love to see this added so I'll tidy it up and create a PR, I don't have a macOS device so I can only speak for Windows.

For my thoughts on the adding it for Windows, doing it inside a dedicated window maybe a issue, the best solution would be to ensure the weathr is always launched inside conhost.exe, this required for Windows 11 if you want to go full screen.

This is what I came up with for making conhost.exe full screen:

    pub fn make_full_screen() -> windows::core::Result<()> {
        unsafe {
            let hwnd: HWND = GetConsoleWindow();

            let style = GetWindowLongW(hwnd, GWL_STYLE);

            let new_style = style
                & !(WS_CAPTION.0 as i32
                    | WS_THICKFRAME.0 as i32
                    | WS_MINIMIZEBOX.0 as i32
                    | WS_MAXIMIZEBOX.0 as i32
                    | WS_SYSMENU.0 as i32);

            SetWindowLongW(hwnd, GWL_STYLE, new_style);

            if !hwnd.0.is_null() {
                ShowWindow(hwnd, SW_MAXIMIZE).unwrap();
            } else {
                println!("No console window found.");
            }

            let handle = GetStdHandle(STD_OUTPUT_HANDLE)?;

            let mut info = CONSOLE_SCREEN_BUFFER_INFO::default();
            GetConsoleScreenBufferInfo(handle, &mut info)?;

            let window_width = info.srWindow.Right - info.srWindow.Left + 1;
            let window_height = info.srWindow.Bottom - info.srWindow.Top + 1;

            SetConsoleScreenBufferSize(
                handle,
                COORD {
                    X: window_width,
                    Y: window_height,
                },
            )?;
        }

        Ok(())
    }

This will break the window if its ran without conhost.exe, even more so in Windows 11 which is why I never created a PR. Since Windows will run a .scr with either of the following cli arguments: /S , /s , /c , /p:[HANDLE] and /c:[HANDLE], this breaks the current CLI argument handling, which admittedly is a easy fix (made even easier by 32f5737
), a major issue is rendering inside the preview window or any window provides by the Windows itself.

Lucky we can just rename a .exe to .scr (as mentioned) and then if the extension is a .scr ignore CLI arguments, respawn into conhost.exe and then go fullscreen. For messaging to weathr, we only have to care about implementing ScreenSaverProc. The screensaver itself must handle exiting on user input