maintenance(oes): close stale net9.0 target review for removed EventSourcing package

[Copilot]

The maintenance inventory flagged Egil.Orleans.EventSourcing for a target framework review (net9.0 across src, Tests, and Tests.AppHost). The inventory snapshot predates the package's removal, so the finding is stale.

Investigation

• The Egil.Orleans.EventSourcing/ directory does not exist; the repo ships only stjm, ot, and stp.
• grep -ril "EventSourcing" returns zero matches across the working tree — no csproj, workflow, docs, or baseline.json entry.
• Commit e68d9db ("chore: remove deprecated libraries and incomplete libraries") deleted exactly the three csproj files named in the issue, plus egil-orleans-eventsourcing-ci.yml, the solution, sources, and version.json.

Outcome

• No code changes. The acceptance criteria are moot — there are no target frameworks to decide on and no CI installing SDKs for this package.
• This issue should be closed as obsolete. The repo's own automation (scripts/maintenance/upsert-issues.ps1 -CloseResolved) auto-closes maintenance issues whose key is no longer produced, so it should resolve on the next inventory run.

If desired, a follow-up could add a guard to the inventory script so it can't emit findings for already-removed packages.