Validate unsupported options on full-text and vector indexes

[Copilot]

Part of #37993

Index options that have no equivalent on the full-text/vector Fluent API (e.g. IsUnique, Filter, IsClustered, DataCompression) could still be set through the Metadata API, where they were silently ignored. This adds model validation so such configuration fails fast.

Changes

• SqlServerModelValidator: added ValidateUnsupportedIndexOptions, invoked from both ValidateFullTextIndex and ValidateVectorIndex. It throws on the first configured option not supported by the corresponding builder API:
  • Core: IsUnique, IsDescending
  • Relational: Filter
  • SQL Server: IsClustered, IncludeProperties, FillFactor, IsCreatedOnline, SortInTempDb, DataCompression
  • The check runs before other index-specific validations so the unsupported-option error takes precedence.
• Resources: FullTextIndexUnsupportedOption / VectorIndexUnsupportedOption added to SqlServerStrings.
• Tests: coverage for full-text (IsUnique) and vector (DataCompression) cases.

Example

modelBuilder.Entity<Blog>(b =>
{
    var index = b.HasFullTextIndex(e => e.Title).UseKeyIndex("PK_Blog");
    index.Metadata.IsUnique = true; // previously ignored, now throws on validation
});

[Copilot]

Pull request overview

This PR adds SQL Server model validation to ensure that index options which are not supported for full-text and vector indexes cannot be configured via the Metadata API (where they were previously silently ignored). When such an option is detected, validation now fails fast with a clear provider-specific error message.

Changes:

• Added a shared ValidateUnsupportedIndexOptions helper in SqlServerModelValidator, invoked for both full-text and vector index validation.
• Introduced new SQL Server resource strings (FullTextIndexUnsupportedOption, VectorIndexUnsupportedOption) and corresponding designer accessors.
• Added tests asserting failures for representative unsupported options on full-text (IsUnique) and vector (DataCompression) indexes.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
test/EFCore.SqlServer.Tests/Infrastructure/SqlServerModelValidatorTest.cs	Adds validation tests for unsupported options on full-text and vector indexes.
src/EFCore.SqlServer/Properties/SqlServerStrings.resx	Adds new localized error message templates for unsupported options.
src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs	Adds strongly-typed accessors for the new resource strings.
src/EFCore.SqlServer/Infrastructure/Internal/SqlServerModelValidator.cs	Implements and wires up unsupported-option validation for full-text and vector indexes.

Files not reviewed (1)

• src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs: Generated file