chore: enhance zip content extraction with posixpath for path normalization

[shaohuzhang1]

chore: enhance zip content extraction with posixpath for path normalization

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[shaohuzhang1]

Code Review

Irregularities and Potential Issues:

1. String Concatenation: The code uses string concatenation (+\n or +) across several statements which can be inefficient due to repeated memory allocation.

2. Variable Names: Some variable names could be more descriptive or unique to avoid confusion between similarly named variables (e.g., md_parts vs image_mode_list).

3. Regular Expressions: While using regular expressions is necessary for parsing Markdown images, they can slow down execution slightly compared to manual splitting with split().

4. Image Reference Handling: There's some repetition in how image references are handled within the loop. Consider creating a function to simplify this logic.

5. Resource Management: Ensure that resources like ZIP files and bytes buffers are properly closed after use. This is implicit here but worth mentioning.

6. Logging: Adding logging might help in debugging and understanding the flow of execution.

7. PosixPath Usage: Using posixpath correctly throughout helps ensure platform-independence when dealing with file paths.

Optimization Suggestions:

1. StringBuilder: Use Python's stringbuilder module instead of manually concatenating strings inside loops for better performance.

from collections import deque

def join_string_parts(parts):
sb = deque()
for part in parts:
sb.append(part)
return ''.join(sb)

Replace existing string concatenations with join_string_parts

2. **Dictionary Comprehension**: If you want to replace references once per document rather than each time an MD block is processed, consider storing matches as dictionary keys.

3. **Avoid Repeated Function Calls**: Store the result of certain operations (like decoding UTF-8), even though it seems unnecessary based on context.

### Conclusion:
The current implementation is robust but can benefit from improvements such as using `join_string_parts`, optimizing reference replacement, and managing resource cleanup more explicitly.