security: enforce verified publisher boundaries and path validation

[ClausValcaTD]

Enforce strict security boundaries in OpenROM-Plugins-Store by:

• Creating verified_publishers.json as the authoritative source of truth for verified publisher IDs.
• Updating build_catalog.py to ignore is_verified / verified manifest fields and strictly evaluate publisher verification status against verified_publishers.json.
• Updating validate_plugin.py to reject community manifests declaring self-verification or exhibiting path mismatches between author ID and directory path.
• Adding .github/CODEOWNERS for protected repository paths.
• Adding unit tests in tests/test_security.py to verify security rules.

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PR created automatically by Jules for task 11989297569302117999 started by @ClausValcaTD

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