chore: add GitHub issue templates

[oco777]

Motivation

• Standardize issue intake to reduce missing information for bug reports, feature requests, docs fixes, and small tasks.
• Provide clear guidance and direct links to Discussions and security policy to route non-issue reports appropriately.

Description

• Add issue forms configuration at /.github/ISSUE_TEMPLATE/config.yml with contact_links for Discussions and security reporting.
• Add a bug report form at /.github/ISSUE_TEMPLATE/bug_report.yml that collects summary, reproduction steps, environment, logs, and confirmations.
• Add feature request, docs improvement, and task templates at /.github/ISSUE_TEMPLATE/feature_request.yml, /.github/ISSUE_TEMPLATE/docs.yml, and /.github/ISSUE_TEMPLATE/task.yml respectively.
• Files were added and committed to the repository with the commit message chore: add GitHub issue templates.

Testing

• No automated tests were run as part of this change.

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Codex Task