v2.7→v2.8 parity: smoke-test BEAUti File/Set working dir menu

[alexeid]

Part of v2.7→v2.8 parity (raised by Remco). Umbrella: #34.

Status

Code is wired — needs a manual test to confirm runtime behavior.

Current state

• beast-fx/src/main/java/beastfx/app/beauti/BeautiTabPane.java:800 — "Set working dir" menu item under File.
• BeautiTabPane.java:1060–1083 — getWorkDirActions() populates submenu dynamically from BEAST directories and calls ProgramStatus.setCurrentDir(dir) on selection.

Work

• Launch BEAUti, open File menu, confirm "Set working dir" is present and submenu is populated.
• Select a directory, confirm subsequent file dialogs default to it.
• Confirm behavior matches v2.7.

Acceptance

• Manual test passes; no code changes expected unless the test reveals a regression.