libSceSaveDataDialog.native technical debt

libSceSaveDataDialog.native shows no UI and ignores progress values. Progress-bar mode (5) stays running until closed, matching Skyrim PPSA03747; other modes finish immediately returning button 1 and first nonempty directory. Console timing and selection remain unverified. Error codes follow shadPS4: sceSaveDataDialogClose returns SAVE_DATA_DIALOG_ERROR_NOT_RUNNING when not running, sceSaveDataDialogGetResult returns SAVE_DATA_DIALOG_ERROR_NOT_FINISHED when not finished (before null/unwritable checks), sceSaveDataDialogTerminate closes running dialogs, and progress updates (sceSaveDataDialogProgressBarInc, sceSaveDataDialogProgressBarSetValue) return SAVE_DATA_DIALOG_ERROR_NOT_RUNNING when not running, rejecting target 0 and rate bounds above 100 with SAVE_DATA_DIALOG_ERROR_PARAM. Parameter size in sceSaveDataDialogOpen is unvalidated as console behaviour is unmeasured.
sceSaveDataDialogIsReadyToDisplay returns 1 unconditionally without checking state, following shadPS4 (savedatadialog.cpp at ce74386283); native console readiness state is unmeasured.

sceSaveDataDialogGetResult (libSceSaveDataDialog.native) - returning SAVE_DATA_DIALOG_ERROR_ARG_NULL for a non-null unwritable result or directory name pointer is a host-safety fallback; console behaviour for unmapped memory is unmeasured. Closes when: measured on a PS5
sceSaveDataDialogOpen (libSceSaveDataDialog.native) - no overlay dialog is drawn for any mode: the layouts of the user message, system message and error code parameters that the SaveDataDialogParam pointers lead to have no source in this repository or measurement on a PS5, so a dialog is not built from them. Closes when: the parameter layouts are measured on a PS5