Adopt the shared issue-backed devguide lifecycle

[LMMV]

What — Bring SMonitor's existing issue-linked bug and proposal reports under the common MolSysSuite lifecycle.\n\nHow — Add common front matter, preserve local queues, archive the resolved import-race report, generate queue/archive indexes, and add an offline validator. Keep the xdist residue blocked by pytest-dev/pytest-xdist#1372.\n\nWhy — SMonitor already has stable issue identities, but status lives only in prose and one resolved report remains in pending_bugs.\n\nRecord — devguide/pending_proposals/adopt_shared_reporting_lifecycle.md\n\nCentral rollout — uibcdf/molsyssuite#13

[LMMV]

Completed by the existing SMonitor adoption in 85c2896 and verified after updating to a6821d9: the devguide report tests pass (15 passed, 2 network skips) and generated indexes are current. The root ambassador guide was then added in 72d9c5d. SMonitor #4 correctly remains blocked upstream and #6 remains open.