Add project quality infrastructure and documentation

[Copilot]

Adds standardized project infrastructure for issue management, automated dependency updates, quality enforcement, and contributor documentation.

GitHub Issue Management

• Templates: Bug report and feature request forms with structured fields
• Configuration: Disabled blank issues, added discussion and documentation contact links
• Dependabot: Grouped weekly updates for GitHub Actions and NuGet dependencies

Quality Enforcement

• Spelling: .cspell.json with project-specific dictionary
• Markdown linting: .markdownlint.json with formatting rules
• CI integration: Quality Checks job runs before build using npx cspell and npx markdownlint-cli

Documentation

• CODE_OF_CONDUCT.md: Contributor Covenant 2.0
• CONTRIBUTING.md: Development workflow, coding standards, and quality check requirements
• SECURITY.md: Vulnerability reporting process and supported versions
• AGENTS.md: AI agent instructions emphasizing absolute URLs in README (required for NuGet package distribution)

README Enhancements

• Added NuGet version badge linking to package
• Converted to markdown reference link format with absolute URLs only
• Added sections linking to contributing guidelines, code of conduct, security policy

All documentation files pass spelling and linting checks. The Quality Checks workflow enforces these standards on future changes.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Project Improvements</issue_title>
<issue_description>The following project improvements are needed:

GitHub issue templates for bug reporting and feature requests with appropriate icons.
GitHub issue template configuration to disable blank issues and add contact links
GitHub dependabot configuration file to keep dependencies updated (grouping dependencies for fewer pull requests)
A .cspell.json file for spelling enforcement
A .markdownlint.json file for enforcing markdown file formatting.
A new "Quality Checks" job added to the build_on_push.yaml file to check spelling and markdown linting
The "Quality Checks" job should use npx to install and run cspell and markdownlint-cli
A standard CODE_OF_CONDUCT.md file should be added
A CONTRIBUTING.md file should be added
A SECURITY.md file should be added
An AGENTS.md file should be added
The README.md file should be improved, and include a badge for NuGet which links to the latest Nuget.org package
All Markdown links should use the Markdown link reference format
The README.md file should only contain absolute URL links as it will be distributed in the NuGet package - this should be documented in the AGENTS.md file and the CONTRIBUTING.md file
The AGENTS.md file should contain instructions that the spelling and markdown linting rules should be followed when performing updates and checked as part of testing the changes.</issue_description>

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

• Fixes Project Improvements #8

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