Implement remaining fileMenu stub verbs for headless mode

[jsavin]

Summary

The following fileMenu verbs are currently stubs that return "not implemented" errors:

• fileMenu.new
• fileMenu.savecopy
• fileMenu.revert
• fileMenu.print
• fileMenu.quit
• fileMenu.saveAs

These need real implementations for headless mode.

Current Behavior

Each stub calls langerrormessage("not implemented") and returns false. The glue scripts in system.verbs.builtins.fileMenu.* dispatch to these via kernel(filemenu.*).

Location

• tests/headless_filemenu_verbs.c — stub implementations (cases filv_new, filv_savecopy, filv_revert, filv_print, filv_quit, filv_saveas)

Priority

P1 — These verbs are part of the fileMenu contract and will be needed for full headless mode functionality.

Related

• PR feat: Implement fileMenu verbs with v7 save format and db corruption fixes #391 implemented fileMenu.open/close/closeall/save
• Issue Restore fldatabasesaveas guard in menu save address update #392 tracks the fldatabasesaveas guard needed before saveAs can work correctly