v2.0.0

• Added a new EFCore.ComplexIndexes.PostgreSQL package with PostgreSQL-specific complex index extensions (GIN, GiST, BRIN, SP-GiST, hash, operator classes, covering columns, concurrent creation, and nulls distinct handling).
• Introduced PostgreSQL design-time services and model differ validation to ensure only supported Npgsql annotations are used during migrations.
• Enhanced complex index handling to carry provider-specific annotations through migrations.
• Added solution-wide NuGet package metadata and build settings via Directory.Build.props.
• Updated tests to cover new provider-annotation serialization and index descriptor signature changes.
• Documented PostgreSQL support and package details in the README.