Add unit tests for console classes

[WarLikeLaux]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues

What does this PR do?

Adds tests for BaseConsole, ExitCode and console Markdown - covers progress bar, ANSI formatting, cursor movement, screen size, wrapText, multi-byte string handling.

Coverage

File	Tests	Lines	Methods	MSI
BaseConsole.php	31 → 53	237/352 (67%) → 340/352 (97%)	33/54 → 53/54	76% (150/196)
ExitCode.php	2	1/1 (100%)	1/1	100% (3/3)
console/Markdown.php	5	5/6 (83%)	5/6	65% (17/26)

12 uncovered lines in BaseConsole are OS-dependent branches in getScreenSize (Windows, macOS stty, tput/ENV fallbacks), streamSupportsAnsiColors (Windows branch) and stdin() (blocks on STDIN read). 1 uncovered line in console/Markdown is renderStrike() which has a pre-existing bug (passes array to Console::ansiFormat).

Escaped mutants (all equivalent)

BaseConsole.php (46): PublicVisibility - L246, always equivalent. CastString x3 - L333/372/374, input is always string. LessThanOrEqualTo/LogicalOr/ReturnRemoval - L368-369, early return produces same empty result via loop. Remaining 38 mutants in getScreenSize (L687-728) and streamSupportsAnsiColors (L659-661) - platform-dependent code, single OS can only exercise one branch.

console/Markdown.php (9): ArrayItemRemoval x4 - ANSI format codes, tests strip formatting before assertion. Concat/ConcatOperandRemoval x4 - newline separators in rendered output. UnwrapRtrim - L65, trailing whitespace not asserted.

Changelog not required, because no source files changed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.87%. Comparing base (379b296) to head (2638e97).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #20782      +/-   ##
============================================
+ Coverage     78.56%   78.87%   +0.30%     
  Complexity    11568    11568              
============================================
  Files           376      376              
  Lines         30750    30750              
============================================
+ Hits          24160    24255      +95     
+ Misses         6590     6495      -95     

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