[philliphoff]

Summary

Raises PackageValidationBaselineVersion in src/Directory.Build.props from 0.8.1 to 0.9.0. 0.9.0 is published on nuget.org, so package validation now compares against it and the APIs added in that release are protected too (docs/versioning.md). There are no CompatibilitySuppressions.xml files to remove.

dotnet pack -c Release passes package validation for EncDotNet.Iso8211, EncDotNet.S57 and EncDotNet.Noaa against the published 0.9.0 packages (net8.0 and net10.0). So everything merged since v0.9.0 (#43–#48, #50–#52) is additive.

Standards alignment

Check each area this PR touches and confirm the matching skill was consulted
(.github/skills/<name>/SKILL.md):

• ISO/IEC 8211 (iso8211)
• S-57 records, topology, updates or exchange sets (s57-enc)
• Legacy chart viewer, maintenance only (chart-viewer)
• N/A: build, CI, docs or tooling only

Standard section references cited in code or docs:

None.

Tests

• Added or updated xUnit tests under tests/
• Test input is built in memory; no real ENC cells are committed
• dotnet test --configuration Release passes locally

EncDotNet.UnitTests passes locally (1091 passed, 1 skipped). Three retained-memory budget tests in EncDotNet.PerformanceTests fail locally (S57Document, S57Chart, Iso8211Document). They fail the same way on unmodified main, and main's CI passed, so this machine's environment causes them, not this change.

Documentation

• Updated the affected package's src/<project>/README.md
• Updated guides under docs/ if user-facing behavior changed
• New public APIs have XML doc comments
• docfx docfx.json --warningsAsErrors passes, if docs changed

Dependencies

• No new NuGet dependencies, OR versions added to
  Directory.Packages.props (not in the .csproj)
• gh-advisory-database security check run for any new dependency

Breaking changes

None

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