feat: configurable grammar discovery and 0.4.1 quality gates

[actbit]

Summary

• add configurable grammar node discovery with NamespaceAndTypeHierarchy, TypeHierarchy, and legacy Namespace modes
• add [GrammarPart(typeof(Root))] for explicit cross-namespace/cross-hierarchy participation
• honor assembly-level [assembly: Skip(...)] patterns
• make Core grammar construction stable through snapshots, defensive RHS copies, and repeatable Build
• remove Generator/Core type-conflict warnings and tighten nullability/test warnings
• fix incremental model equality so Mode, skip patterns, token diagnostics, and discovery changes invalidate generation
• make multiple [Grammar(Mode = ...)] declarations generate independently and support nodes shared by multiple grammar roots
• prevent source hint and partial-generation collisions across namespaces and grammars
• validate attribute identity and token constructor accessibility precisely
• bump the package version to 0.4.1 and document the new behavior in Japanese and English
• run the full test suite in CI and before NuGet publication with the .NET 10 SDK pinned

Why

Grammar extraction previously depended on a same-namespace scan. That prevented natural project layouts and offered no way to disable namespace-based discovery. The new modes preserve compatibility while allowing hierarchy-only or explicit discovery.

The repository also lacked a full-test quality gate before package publication, and Core builder results could retain mutable builder collections.

Impact

The default remains compatible with same-namespace grammars and additionally discovers root-derived nodes across the assembly. Users who want no namespace scan can select GrammarDiscovery.TypeHierarchy; exceptional nodes can opt in with GrammarPart.

Multiple grammar modes on the same root now emit each Lexer/Parser while sharing node partial generation safely. Nodes participating in multiple grammar roots emit one partial, while grammar-specific [OnReduce] hooks remain in the corresponding parser. Fully qualified, deterministic source hint names avoid collisions between same-named roots or nodes in different namespaces.

This is a patch release and keeps the existing Production.Rhs public API type unchanged.

Validation

• dotnet test AstFirst.slnx -c Release --no-restore --nologo — 374 passed
• packed AstFirst.Core, AstFirst.Runtime, and AstFirst 0.4.1 successfully
• compatibility smoke test passed on net6.0, net8.0, and net10.0
• git diff --check passed

Self-review

The self-review caught and fixed incremental-cache omissions, an unpinned publish SDK, stale performance/error-recovery documentation, the previously ignored assembly-level Skip attribute, source hint collisions, multiple-mode model collapsing, shared-node partial duplication, attribute-name false positives, and inaccessible token-constructor diagnostics. Invalid-signature diagnostics remain separate follow-up work.