feat(ci): add toolchain version probe and improve breach monitor accuracy (#220)

* fix(ci): improve breach monitor accuracy — add ecosystems, fix advisory queries, versioned checks

* feat(ci): add toolchain version probe workflow; breach monitor reads pinned versions

* fix(ci): address PR review — fix NVD allowlist, empty-tools guard, version severity logic, CVE triage detail

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Co-authored-by: Dima Birenbaum <dbirenbaum@microsoft.com>

Author: DimaBir