Fix parent non-recursive arguments leaking into subcommands (#2785)

[AhmedMyoussif]

Description

This PR resolves issue #2785 where non-recursive positional arguments from parent commands were incorrectly inherited, validated, and displayed in subcommands.

Key Changes

• Early Interception in ParseOperation: Introduced MoveNonRecursiveParentArgumentsToUnmatched inside ParseSubcommand(). When entering a subcommand, the parser immediately intercepts parent arguments configured with Recursive = false, purges them from the SymbolResultTree, and registers their tokens as UnmatchedTokens under the root command result. This completely prevents validation leaks and downstream crashes.
• Help Architecture Alignment: Updated HelpBuilder.cs (GetUsageParts and GetCommandArgumentRows) to filter out parent arguments where Recursive == false when rendering usage strings and argument tables for subcommands.
• Public API Contract: Added the Recursive property to the Argument class (defaulting to true to avoid breaking changes) and updated the alphabetical baseline file for API compatibility checks.
• Test Coverage: Added dedicated unit tests for both parsing telemetry (ParserTests.cs) and layout rendering accuracy (HelpBuilderTests.cs).

Verification

• Tested locally on net10.0 target.
• All 929 test cases passing successfully.

[AhmedMyoussif]

@dotnet-policy-service agree