feat: capture console output in test failure messages

[Copilot]

Console output from tests was only visible in the Test Results panel, not in inline failure messages where developers typically debug.

Implementation

• Buffer stdout lines preceding test result markers (✓ 1) test name)
• Associate buffered output with test items via Map
• Filter lab structural output (test durations, leak detection)
• Prepend console output to TestMessage with header when tests fail

// Before
run.failed(testItem, new vscode.TestMessage(errorMessage), duration);

// After  
const consoleOutput = consoleOutputPerTest.get(testItem);
const message = formatMessageWithConsoleOutput(errorMessage, consoleOutput);
run.failed(testItem, new vscode.TestMessage(message), duration);

Output Format

Failure messages now include:

Console output:
DEBUG: variable state = { foo: 'bar' }
DEBUG: condition evaluated to false

Expected 1 to equal 2
  at test.js:10:5

Notes

• Lab executes tests sequentially - output buffering assumes this
• Test Results panel behavior unchanged
• Per-test isolation maintained for describe blocks with multiple children

Original prompt

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This section details on the original issue you should resolve

<issue_title>Show console.log output in extension output panel or inline failure message</issue_title>
<issue_description>For debugging purposes, console.log statements within tests are not currently visible in the extension.

Current behaviour

Console output from tests is not captured or displayed anywhere accessible via the extension.

Suggested behaviour

Pipe console.log output to one or both of:

1. The extension's output panel
2. The inline failure message that appears in the editor

This would significantly improve the debugging experience when tests fail.

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Feedback from Kevin Paxton</issue_description>

<agent_instructions>ensure commits are in semantic release format</agent_instructions>

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

• Fixes Show console.log output in extension output panel or inline failure message #34

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