Refactor Grid.Body to extend Component.Base and use internal Row Pool

Objective: Revert Neo.grid.Body inheritance from Neo.container.Base to Neo.component.Base. The new "Fixed-DOM-Order" Row Pooling strategy renders the Container API (add, remove, layout) unsafe and redundant.

Changes Required:

1. Inheritance:

   • Change src/grid/Body.mjs to extend Neo.component.Base.

2. Row Pool Management:

   • Replace the items config with a private/protected class field (e.g., items = []) to store Neo.grid.Row instances.
   • Update createRowPool to instantiate rows with:

             parentId: me.id,
       appName : me.appName,
       windowId: me.windowId,
       theme   : me.theme

3. Lifecycle Management:

   • Implement destroy() to manually iterate and destroy row instances in this.items.

4. Config Propagation (Container Behavior Mimicry):

   • Implement afterSetAppName, afterSetMounted, afterSetTheme, and afterSetWindowId.
   • These methods must iterate over this.items and update the corresponding properties on the row instances, ensuring correct state propagation (theme changes, window moves, etc.).

5. Verification:

   • Ensure Neo.manager.Component methods (down, query) still function correctly by relying on the parentId link.

Why: To enforce API safety by hiding inapplicable container methods and to remove the overhead of unused layout/container logic in the highly performance-sensitive grid body.