Fix markdown code region balancer treating indented examples as nested fences

[Copilot]

Investigation: JavaScript Code Region Balancer Bug

Problem

The markdown code region balancer function fails to properly balance content from GitHub issue #11081.

Progress

• Understand the current balancer algorithm
• Identify the specific logic flaw
• Create focused test cases that reproduce the issue
• Add indentation checking for nested block closers
• Implement two-pass algorithm to respect block boundaries
• Format and lint JavaScript files
• Fix issue with consecutive code blocks being treated as nested
• Validate fix with existing tests
• Test with actual issue [CI Failure Doctor] JS Test Suite Failure - 44 Tests Failing After PR #11053 (handle_agent_failure changes) #11081 content
• Run full test suite

Current Status

• Formatted JavaScript files using make fmt-cjs
• All files now pass linting (make lint-cjs)
• Minor formatting fix: removed trailing whitespace in markdown_code_region_balancer.cjs

Known Issue

Algorithm still needs refinement for consecutive separate blocks being treated as nested.

Original prompt

Investigate why the javascript code region balancer function was not able to balance the description in this issue:

#11081

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[pelikhan]

@copilot format, lint js

[Copilot]

@copilot format, lint js

Done! Formatted and linted JavaScript files. All files now pass linting checks. Commit: 36723f6