Bug 45: Split Button — Popup Menu

WCAG 1.3.1 (Info and Relationships), 4.1.2 (Name, Role, Value) | Menu trigger button not clearly labeled.

Bug: Menu Trigger No aria-label

Bug: Menu Items Not Semantic

Bug: Dropdown State Not Clear

How HAL Fixes This: HAL detects split button menus and adds aria-label to the trigger button (e.g., "Export options" or "Filter menu"). It also adds aria-expanded and aria-haspopup="menu", and ensures the menu itself has role="menu" with items having role="menuitem".