Add GitHub issue and PR templates and update SECURITY

[jamespepper81]

This pull request introduces a comprehensive set of GitHub issue and pull request templates, as well as updates to the security policy, to improve project contribution workflows and communication. The changes standardize how bugs, feature requests, and documentation issues are reported, clarify security procedures, and provide clear guidance for contributors.

Issue and PR Template Additions:

• Standardized Issue Templates:

  • Added .github/ISSUE_TEMPLATE/bug_report.yml for structured bug reporting, including required fields for reproduction steps, platform, version, and device details.
  • Added .github/ISSUE_TEMPLATE/feature_request.yml for feature/enhancement suggestions, capturing problem statements, use cases, and priorities.
  • Added .github/ISSUE_TEMPLATE/documentation.yml to report or suggest improvements to documentation, specifying type and location.
  • Updated .github/ISSUE_TEMPLATE/config.yml to disable blank issues and add links for discussions and private security reporting.

• Pull Request Template:

  • Introduced .github/PULL_REQUEST_TEMPLATE.md to guide contributors through PR descriptions, testing, security considerations, and checklists, ensuring high-quality and consistent submissions.

Security Policy Update:

• Enhanced SECURITY.md:
  • Updated supported versions table to reflect current BitSleuth Wallet releases.
  • Provided clear, private reporting instructions for vulnerabilities, including response timelines and scope of security issues.
  • Outlined the project's security best practices and clarified what is considered in/out of scope for vulnerability reports.