Fix cursor positioning when Console.BufferWidth exceeds Console.WindowWidth

[Copilot]

When Console.BufferWidth is set larger than Console.WindowWidth, test progress timings display incorrectly or not at all. MTP uses ANSI cursor positioning to place timings on the right edge, but was calculating positions using BufferWidth instead of WindowWidth.

Changes

IConsole interface

• Added WindowWidth and WindowHeight properties

Terminal implementations

• SimpleTerminal and AnsiTerminal now use WindowWidth/WindowHeight instead of BufferWidth/BufferHeight for their Width/Height properties
• ANSI cursor positioning now operates within visible window bounds

Tests

• Added SimpleTerminal_UsesWindowWidthNotBufferWidth and AnsiTerminal_UsesWindowWidthNotBufferWidth to verify behavior when buffer ≠ window dimensions
• Updated test mocks to implement new interface properties

Example scenario

// Setting large buffer width (e.g., in Windows Terminal)
Console.BufferWidth = 4096;  // Buffer width
// Console.WindowWidth = 120; // Actual visible width

// Before: Cursor positioned at column 4096 - timing_length (off-screen)
// After:  Cursor positioned at column 120 - timing_length (visible)

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Microsoft Testing Platform does not handle large BufferWidth in console</issue_title>
<issue_description>## Describe the bug

When Console.BufferWidth is set to a larger value than the Console.WindowWidth, the running test timing is not displayed correctly (or at all).

If using Windows Terminal, the output is messed up. If using conhost.exe, then the timings do not appear.

Steps To Reproduce

Using TUnit:

dotnet new console
dotnet add package tunit

Add the following test fixture:

using System.Runtime.InteropServices;

public class Fixture
{
    [Test]
    public async Task Test1()
    {
        await Task.Delay(TimeSpan.FromSeconds(2));

        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            Console.BufferWidth = 4096;

        await Task.Delay(TimeSpan.FromSeconds(2));
    }

    [Test]
    public Task Test2() => Task.Delay(TimeSpan.FromSeconds(3));
}

Expected behavior

I expect to be able to see the timings as intended while the tests are running (i.e., updated every few seconds, but then removed after the final test run completes).

Actual behavior

If using Windows Terminal, the output is skewed:

testfx_wt.mp4

If using conhost.exe, the timing is not visible.

Additional context

Testing platform is using ANSI codes to position the cursor at the right-hand side of the screen. However, the calculations are done using Console.BufferWidth ... should they perhaps be using Console.WindowWidth to position the output of the test timing?

Or perhaps the timings should be moved to the beginning of the updating output so there's no reliance on the screen/buffer width calculations?
</issue_description>

<agent_instructions>Assess if the analysis of the issue is correct, if that's the case suggest a fix and ensure to have tests to avoid regressions</agent_instructions>

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

• Fixes Microsoft Testing Platform does not handle large BufferWidth in console #7240

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