docs(plugin): freeze manifest and trust policy v1 contract

[ExplodingUFO]

Summary

• publish EN/ZH plugin manifest and trust policy v1 contract docs
• link host integration, plugin recipe, and consumer sample to the new contract page
• lock the contract with docs regression tests and minimal runtime-surface assertions

Verification

• dotnet test tests/AsterGraph.Editor.Tests/AsterGraph.Editor.Tests.csproj -nologo -v minimal --filter "FullyQualifiedNameGraphEditorPluginContractsTests|FullyQualifiedNameGraphEditorPluginDiscoveryTests|FullyQualifiedNameGraphEditorPluginInspectionContractsTests|FullyQualifiedNameGraphEditorPluginLoadingTests|FullyQualifiedName~GraphEditorPluginPackageStagingTests"
• dotnet test tests/AsterGraph.ConsumerSample.Tests/AsterGraph.ConsumerSample.Tests.csproj -nologo -v minimal --filter "FullyQualifiedName~ConsumerSampleProofTests"
• dotnet test tests/AsterGraph.Demo.Tests/AsterGraph.Demo.Tests.csproj -nologo -v minimal --filter "FullyQualifiedNameDemoCapabilityShowcaseTests|FullyQualifiedNameDemoProofReleaseSurfaceTests|FullyQualifiedName~PluginTrustContractDocsTests"
• pwsh -File eng/ci.ps1 -Lane contract -Framework all -Configuration Release