Add KeysUniqueAcrossSchemas property to SharedTableConvention

[Copilot]

When KeysUniqueAcrossTables is true, key constraint names are currently enforced unique across all tables regardless of schema. Databases like PostgreSQL scope constraint name uniqueness per-schema, so this produces unnecessary renames. See npgsql/efcore.pg#3704.

• Add protected virtual bool KeysUniqueAcrossSchemas => true to SharedTableConvention, following the existing *UniqueAcrossTables property pattern
• Group the table iteration in ProcessModelFinalizing by schema; clear the keys dictionary at schema boundaries when KeysUniqueAcrossSchemas is false
• Order schema groups by schema name and tables within each group by table name for deterministic iteration
• Default true preserves existing behavior; providers override to false as needed
• Add SharedTableConventionTest with tests verifying both the override to false (keys not uniquified across schemas) and the default true behavior (keys uniquified across schemas), using the finalized model for assertions

// In a provider-specific convention (e.g. NpgsqlSharedTableConvention):
protected override bool KeysUniqueAcrossSchemas => false;

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[Copilot]

Pull request overview

Adds a new KeysUniqueAcrossSchemas customization point to SharedTableConvention and introduces tests validating key name uniqueness behavior across schemas.

Changes:

• Introduce SharedTableConvention.KeysUniqueAcrossSchemas (default true) to control key name uniqueness across schemas.
• Update ProcessModelFinalizing to optionally reset key-name uniquification per schema.
• Add tests covering both default behavior and KeysUniqueAcrossSchemas = false.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/EFCore.Relational/Metadata/Conventions/SharedTableConvention.cs	Adds KeysUniqueAcrossSchemas and changes table iteration to support per-schema key uniquification.
test/EFCore.Relational.Tests/Metadata/Conventions/SharedTableConventionTest.cs	Adds tests asserting key name behavior across schemas for both default and overridden convention behavior.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

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