Document breaking changes for MigrationsNotFound default throw and EFOptimizeContext removal

[Copilot]

Documents two EF Core 11 breaking changes in entity-framework/core/what-is-new/ef-core-11.0/breaking-changes.md:

• Low impact — MigrationsNotFound now throws by default (efcore#35218): RelationalEventId.MigrationsNotFound changed from Information log to Error with default Throw behavior, consistent with the PendingModelChangesWarning treatment from EF 9.0. Mitigation:

  options.ConfigureWarnings(w => w.Ignore(RelationalEventId.MigrationsNotFound))

• Low impact — EFOptimizeContext MSBuild property removed (efcore#35079): Redundant property removed; EFScaffoldModelStage and EFPrecompileQueriesStage are the sole controls for code generation. PublishAOT=true enables generation automatically during publish.

Also updates the MSBuild integration page (entity-framework/core/cli/msbuild.md) to note that EFOptimizeContext only applies to EF Core 9-10 and was removed in EF Core 11.

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[Copilot]

Pull request overview

This PR documents two new EF Core 11 breaking changes in the existing breaking-changes.md page. The entries describe: (1) MigrationsNotFound event now throwing by default instead of logging informational message, and (2) removal of the redundant EFOptimizeContext MSBuild property.

Changes:

• Added a medium-impact breaking change entry for MigrationsNotFound default throw behavior, including migration guidance using ConfigureWarnings
• Added a low-impact breaking change entry for EFOptimizeContext removal, documenting the replacement properties EFScaffoldModelStage and EFPrecompileQueriesStage
• Updated the summary table at the top of the page with links to both new entries

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[AndriySvyryd]

@copilot Also update the MSBuild integration page, noting that the changes only apply for 11+

[Copilot]

@copilot Also update the MSBuild integration page, noting that the changes only apply for 11+

Updated the MSBuild integration page (entity-framework/core/cli/msbuild.md) in 2009bbd. Added version-specific notes:

• EFOptimizeContext: marked as "EF Core 9-10 only; removed in EF Core 11"
• EFScaffoldModelStage and EFPrecompileQueriesStage: added notes about EF Core 9-10 requiring EFOptimizeContext vs EF Core 11+ working independently
• Added a [!NOTE] block linking to the breaking changes documentation