[MAINT]: Add CODEOWNERS, issue/PR templates, and update README

[spencrr]

Description

Add community health files and update README with badges and improved formatting.

CODEOWNERS (.github/CODEOWNERS):

• Assigns @microsoft/ai-red-team-dev as default reviewers for all files

Issue templates (.github/ISSUE_TEMPLATE/):

• bug_report.yml structured form with description, repro steps, expected/actual
  behavior, Python version, OS, and RAMPART version fields
• feature_request.yml summary, motivation, proposed solution, alternatives, context
• config.yml disables blank issues to enforce template usage
• doc_improvement.yml documentation improvement request template
• other.yml catch-all template for issues that do not fit other categories

PR template (.github/PULL_REQUEST_TEMPLATE/):

• Description, breaking changes, and checklist sections
• Header comments documenting the conventional commit pattern for squash messages

README (README.md):

• Centered title and subtitle
• Badge row:
  • OpenSSF Scorecard (on public access)
  • CI status
  • PyPI version, Python versions, MIT license (all derived from PyPI, dependent on pkg name)

Breaking changes

None

Checklist

• pre-commit run --all-files passes
• Tests added or updated for changes
• Documentation updated

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

What Enabling Code Scanning Means:

• The 'Security' tab will display more code scanning analysis results (e.g., for the default branch).
• Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results.
• You will be able to see the analysis results for the pull request's branch on this overview once the scans have completed and the checks have passed.

For more information about GitHub Code Scanning, check out the documentation.

[nina-msft]

Looks like great additions! I left some non-blocking questions on the utility of the links for our README audience, feel free to respond in comment or DM :-)