Fix: Preserve newlines in code blocks with github flavor

[yeoldegrove]

Summary

Fixes a bug where markdown_flavor = "github" unconditionally collapses all newlines into spaces, breaking multi-line content in code blocks, doctest blocks, math blocks, and comments.

Problem

Commit 7c4daaf introduced a workaround for GitHub-flavored markdown treating newlines as <br/> in paragraphs. However, the implementation in visit_Text() unconditionally replaces all \n characters with spaces when markdown_flavor == "github", including text inside literal_block nodes (fenced code blocks) where newlines are semantically required.

Example Impact

Multi-line argparse usage text from sphinxcontrib-autoprogram:

Before (broken):

usage: command [-h] [--option1 VALUE1]                  [--option2 VALUE2]                  [--option3 VALUE3]                  argument

After (fixed):

usage: command [-h] [--option1 VALUE1]
               [--option2 VALUE2]
               [--option3 VALUE3]
               argument

Root Cause

The visit_Text method in translator.py:349 only checked self.config.markdown_flavor without considering whether the translator was inside a verbatim context.

The visit_literal_block method already pushes a status with escape_text=False to signal "we're inside a verbatim block", but this flag was not being checked.

Solution

Add and self.status.escape_text to the condition on line 349:

# Before:
if self.config.markdown_flavor == "github":
    text = text.replace("\n", " ")

# After:
if self.config.markdown_flavor == "github" and self.status.escape_text:
    text = text.replace("\n", " ")

This ensures newlines are only collapsed in normal prose paragraphs (where escape_text=True), not in code/math/comment blocks (where escape_text=False).