docs(ms-ai-architect): legg til SECURITY.md (AAA+ runde 3, C-aksen)

Ny SECURITY.md i repo-roten etter felles mal for de 15 repoene i denne
runden. Ingen versjon, tag eller katalog-ref endret.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BNpxhzuf5mydYeoQZ53wJw

SECURITY.md

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+# Security policy
+
+## Reporting a vulnerability
+
+Report privately to <security@fromaitochitta.com> - do not open a
+public issue.
+Canonical repository: https://git.fromaitochitta.com/open/ms-ai-architect
+
+Please include the affected version or commit, a minimal reproduction,
+and the impact you see. We acknowledge every report within 5 working
+days, agree a fix and disclosure timeline with the reporter, and aim to
+disclose within 90 days of the initial report.
+
+## Response process
+
+1. Acknowledge within 5 working days.
+2. Triage and confirm severity within 10 working days.
+3. Develop and test a fix.
+4. Publish an advisory and credit the reporter unless they prefer
+   to remain anonymous.
+
+## Supported versions
+
+The latest tagged release (currently 1.17.0) is the only supported
+version. Security fixes land on `main` and are released as a new tag;
+we do not backport fixes to older releases. See `CHANGELOG.md` for the
+release history.
+
+## Advisories
+
+We publish advisories for confirmed vulnerabilities once a fix is
+available, crediting the reporter unless they request anonymity.