Avoid redundant settings for nested Python projects

[Copilot]

Nested projects were persisted even when they used the same environment and package managers as their nearest parent. This created unnecessary pythonProjects overrides instead of relying on inherited configuration.

• Inheritance-aware persistence

  • Resolve the nearest parent within the same workspace.
  • Treat the workspace root as an implicit default-configured parent.
  • Save a child override only when either manager differs.

• Existing overrides

  • Preserve matching child entries.
  • Remove stale child entries when the requested defaults can be inherited.

• Multi-root workspaces

  • Resolve parents using both workspace and path.
  • Include the workspace discriminator when a child override is required.

• Fixes Bug: Children Projects in Settings #401