[059] Create SECURITY.md documentation

[konard]

Parent epic: #1

Phase: Security and Licenses
Priority: 59

Scope

Publish security policy documentation for reporting vulnerabilities, supported versions, and responsible disclosure.

Implementation Steps

• Add SECURITY.md with vulnerability reporting and supported version guidance.
• Document expectations for secrets, private reports, and disclosure timelines.
• Link security policy from contributor and release documentation.

Acceptance Criteria

• SECURITY.md exists and explains how to report vulnerabilities privately.
• Supported versions and disclosure expectations are documented.
• Human maintainers review the security policy before release.

Automation

Generated from #1 using scripts/decompose-epic.mjs.