Fix NuGet publish workflow YAML parsing

[tadoEng]

Release-infrastructure repair discovered while preparing EtabSharp 0.3.6-beta after #2.

Base: 8887133858c7f7249c3a01a27f839649b9b49226
Head: d6a67151cb5685b50479facabfa6c9dd035b9571

The existing publish-nuget.yml was syntactically invalid: the PowerShell here-string contents were flush-left and escaped the YAML run: | block; the file also ended with an unnecessary second-document marker. Evidence: pushes produced immediate failed workflow runs with zero jobs, including master merge run 31674708488.

This PR only repairs YAML structure by indenting the existing IL here-string under run: | and removing the trailing document marker. No EtabSharp production/test/package code changes.

Validation: pushing refreshed head d6a6715 produces zero workflow runs, as expected because the now-valid workflow is tag-only (push.tags: v*).

This must merge before creating v0.3.6-beta.

[tadoEng]

Release follow-up after v0.3.6-beta attempt at master 18a57fbd314b78013cbdee1fc4f912fb57387947.

Publish run 31675177596 reached Build and failed before tests/version extraction/pack/push/release. Nothing was published; NuGet remains 0.3.5-beta and no GitHub release exists.

Root cause is a pre-existing ETABSv1 reference-resolution mismatch in two solution consumers, not EtabSharp #2:

• test/EtabsSharp.VisualTest/EtabsSharp.VisualTest.csproj
• mcp/EtabSharp.Mcp/EtabSharp.Mcp.csproj

Both resolve only C:\Program Files...\ETABS 22\ETABSv1.dll, so CI picks up the workflow's minimal stub and their real ETABS API usages fail compilation. src/EtabSharp and test/EtabSharp.Test prefer the tracked repo lib\ETABSv1.dll and therefore compile.

Lead decision: keep the whole-solution build; do not narrow CI to src/EtabSharp. Repair those two projects to mirror the accepted resolution order used by EtabSharp.Test: repo-local lib\ETABSv1.dll first, then ETABS 24 x64/x86, 23 x64/x86, 22 x64/x86. No production library code, workflow redesign, version bump, tag movement, publish, or live ETABS in that PR.

Keep the failed v0.3.6-beta tag at 18a57f... until the repair PR is exact-head reviewed and merged. Then delete/recreate the same tag at the accepted new master because no package/version was published.