Fixed FileStream access to least required permissions

[Crypt32]

PR Classification

Code cleanup and minor improvement for file handling.

PR Summary

This pull request consolidates using directives and clarifies file access in the FileUtility class. It improves code readability and ensures explicit file access mode.

• FileUtility.cs: Consolidated using directives into a single line and added necessary imports.
• FileUtility.cs: Updated FileStream instantiation to explicitly use FileAccess.Read.

[Copilot]

Pull request overview

This PR updates FileUtility to open files with explicit read-only access when probing the file header, aligning file handling with least-required permissions and improving clarity around access intent.

Changes:

• Removes the leading BOM/indentation artifact on the first using line.
• Updates the header-probe FileStream construction to explicitly use FileAccess.Read.

Comments suppressed due to low confidence (1)

src/Asn1Editor/API/Utils/FileUtility.cs:44

• The BOM/encoding detection below uses buffer[2] and buffer[3], but the current guard only throws when readBytes < 2. If the file is 2–3 bytes long, the remaining buffer bytes stay 0 (array initialization), which can cause incorrect matches (e.g., UTF-32 check) and misclassify the input. Track readBytes outside the using-block and gate each BOM check by the required byte length (>=3 or >=4).

            Int32 readBytes = fs.Read(buffer, 0, 4);
            if (readBytes < 2) {
                throw new Exception("The data is invalid");
            }

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.