[007] Add CODEOWNERS for automatic reviewer assignment

[konard]

Parent epic: #1

Phase: Infrastructure and Core
Priority: 7

Scope

Add CODEOWNERS coverage for repository areas so security, platform, and release changes request the right reviewers.

Implementation Steps

• Map repository paths to owner groups or maintainers.
• Add CODEOWNERS entries for security, CI, docs, platform wrappers, and shared code.
• Document how ownership changes are reviewed.

Acceptance Criteria

• CODEOWNERS exists and covers high-risk paths.
• Security and release paths require human review ownership.
• Ownership rules are documented for future maintainers.

Automation

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