Fix: Create test_images directory if it doesn't exist

[Copilot]

Fixes an issue where the convert() function would fail when trying to save PNG files to the test_images directory in fresh git clones or installations where this directory doesn't exist.

Problem

The convert() function in crates/crust-core/src/convert.rs generates PNG filenames using paths like ./test_images/{timestamp}.png via the unique_timestamp() function. However, the function attempts to save files to this directory without ensuring it exists first, causing the save operation to fail with a directory not found error in fresh installations.

Solution

Added automatic directory creation before attempting to save PNG files:

// Ensure the test_images directory exists
if let Err(e) = fs::create_dir_all("./test_images") {
    error!("Failed to create test_images directory: {}", e);
    std::process::exit(1);
}

The fix uses fs::create_dir_all() which:

• Creates the directory if it doesn't exist
• Succeeds silently if the directory already exists (idempotent)
• Creates parent directories if needed
• Maintains consistent error handling with the existing code pattern

Changes

• Added use std::fs; import
• Added directory creation logic before the PNG save operation
• Maintains existing error handling patterns using tracing::error and std::process::exit(1)

This ensures users can successfully run the conversion process immediately after cloning the repository without manual directory creation.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/doubleailes/ogawa-rs/commits/HEAD
  • Triggering command: /home/REDACTED/.rustup/toolchains/1.89.0-x86_64-REDACTED-linux-gnu/bin/cargo check (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Create test_images folder if it does not exist</issue_title>
<issue_description>The folder test_images used in the convert process to png maybe not exist in a fresh git clone or install.

It can be great if can be create in case in does not exist already</issue_description>

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

Fixes #86

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